Mar. 2018, JPSJ Outstanding Referee, 日本物理学会
Official journal

Sep. 2007, 第12回論文賞, "Evidence for Magnetic-Field-Induced Quadrupolar Ordering in the Heavy-Fermion Superconductor PrOs4Sb12," J. Phys. Soc. Jpn., Vol.72, No.5 pp1002 (2003)., 日本物理学会
神木正史;岩佐和晃;中島基樹;目時直人;荒木新吾;Nick BERNHOEFT;Jean-Michel MIGNOT;Arsen GUKASOV;佐藤英行;青木勇二;菅原仁
Official journal

〔Major achievements〕Antiferromagnetic ordering and chiral crystal structure transformation in Nd3Rh4Sn13
Ami Shimoda; Kazuaki Iwasa; Keitaro Kuwahara; Hajime Sagayama; Hironori Nakao; Motoyuki Ishikado; Akiko Nakao; Seiko Ohira-Kawamura; Naoki Murai; Takashi Ohhara; Yusuke Nambu, Corresponding
Physical Review B, Apr. 2024, [Reviewed]

〔Major achievements〕Superconductivity in chiral cubic Y3Rh4Ge13
Md Asif Afzal; Ryuji Higashinaka; Kazuaki Iwasa; Nazir Ahmed; Ryo Tsubota; Naoki Nakamura; Tatsuma D. Matsuda; Yuji Aoki
Journal of Alloys and Compounds, Mar. 2024, [Reviewed]

〔Major achievements〕Magnetic Ordering and Structural Phase Transitions of Nd3T4Sn13 (T = Rh and Ir)
Ami Shimoda; Kazuaki Iwasa; Keitaro Kuwahara; Hajime Sagayama; Hironori Nakao; Motoyuki Ishikado; Takashi Ohhara; Akiko Nakao; Akinori Hoshikawa; and Toru Ishigaki, Corresponding, The Physical Society of Japan
JPS Conf. Proc., May 2023, [Reviewed]

〔Major achievements〕Weyl–Kondo semimetal behavior in the chiral structure phase of Ce3Rh4Sn13
Kazuaki Iwasa; Kazuya Suyama; Seiko Ohira-Kawamura; Kenji Nakajima; Stéphane Raymond; Paul Steffens; Akira Yamada; Tatsuma D. Matsuda; Yuji Aoki; Ikuto Kawasaki; Shin-ichi Fujimori; Hiroshi Yamagami; and Makoto Yokoyama, Lead, APS
Physical Review Materials, Jan. 2023, [Reviewed]

〔Major achievements〕Multipole polaron in the devil’s staircase of CeSb
Y. Arai; Kenta Kuroda; T. Nomoto; Z. H. Tin; S. Sakuragi; C. Bareille; S. Akebi; K. Kurokawa; Y. Kinoshita; W.-L. Zhang; S. Shin; M. Tokunaga; H. Kitazawa; Y. Haga; H. S. Suzuki; S. Miyasaka; S. Tajima; K. Iwasa; R. Arita and Takeshi Kondo, Springer Nature Limited
Nature Materials, Feb. 2022, [Reviewed]

〔Major achievements〕Magnetic excitations in chiral-structure phase of Ce₃Ir₄Sn₁₃
Iwasa, K.; Nakazato, S.; Hashimoto, D.; Shiozawa, M.; Kuwahara, K.; Sagayama, H.; Ohira-Kawamura, S.; Murai, N.; Adroja, D.T.; Strydom, A.M., Lead, The Physical Society of Japan
Journal of the Physical Society of Japan, Nov. 2021, [Reviewed]

Direct observation of modulation of p-f hybridization in unconventional ordered phase of PrRu₄P₁₂
Nakao, H.; Iwasa, K., The Physical Society of Japan
Journal of the Physical Society of Japan, May 2020, [Reviewed]

Successive Phase Transitions in R3Ir4Sn13 (R: La and Ce) Investigated Using Neutron and X-ray Diffraction
Seiya Nakazato; Kazuaki Iwasa; Daisuke Hashimoto; Mami Shiozawa; Keitaro Kuwahara; Hironori Nakao; Hajime Sagayama; Motoyuki Ishikado; Takashi Ohhara; Akiko Nakao; Koji Munakata; Ryoji Kiyanagi, Journal of the Physical Society of Japan
Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2019), Mar. 2020, [Reviewed]

〔Major achievements〕Neutron Scattering Studies on 4f2-Electron Multipoles in Pr-based Systems (SPECIAL TOPICS: New Frontiers in Physics with Spin, Orbital, and Atomic Correlations Using Neutron Scattering)
Kazuaki Iwasa, The Physical Society of Japan
J. Phys. Soc. Jpn., Mar. 2019, [Reviewed], [Invited]

Neutron Scattering Studies on 4f²-Electron Multipoles in Pr-based Systems
Iwasa, K.
Journal of the Physical Society of Japan, 2019

Neutron diffraction studies on valence ordering compound YbPd
Oyama, K.; Sugishima, M.; Tanabe, K.; Mitsuda, A.; Wada, H.; Ohoyama, K.; Matsukawa, T.; Yoshida, Y.; Hoshikawa, A.; Ishigaki, T.; Iwasa, K., The Physical Society of Japan
Journal of the Physical Society of Japan, Oct. 2018, [Reviewed]

Quantum Paramagnet Near Spin-State Transition
Keisuke Tomiyasu; Naoko Ito; Ryuji Okazaki; Yuki Takahashi; Mitsugi Onodera; Kazuaki Iwasa; Tsutomu Nojima; Takuya Aoyama; Kenya Ohgushi; Yoshihisa Ishikawa; Takashi Kamiyama; Seiko Ohira-Kawamura; Maiko Kofu; Sumio Ishihara, John Wiley & Sons, Inc.
Adv. Quantum Technol., Oct. 2018, [Reviewed]

〔Major achievements〕Chiral-crystal-structure transformations and magnetic states of R3Rh4Sn13 (R= la and Ce)
Suyama, K.; Iwasa, K.; Otomo, Y.; Tomiyasu, K.; Sagayama, H.; Sagayama, R.; Nakao, H.; Kumai, R.; Kitajima, Y.; Damay, F.; Mignot, J.-M.; Yamada, A.; Matsuda, T.D.; Aoki, Y., Corresponding, APS
Physical Review B, Jun. 2018, [Reviewed]

Resonant x-ray scattering study on electronic hybridization in unconventional ordered phase of PrRu4P12
Hironori Nakao; Chihiro Tabata; Kazuaki Iwasa, PrRu4P12, which undergoes a metal-insulator transition at TMI ∼ 63 K, has been investigated by resonant x-ray scattering technique at the Pr L 3-edge, the P K-edge, and the Ru L 3-edge, in which element and orbital selective electronic states can be clarified. Resonating energy spectra at the 111 reflection were found at the Pr L 3-edge and P K-edge, while it was not observed at the Rh L 3-edge. This is the first observation of quite large resonant signal at the P K-edge. This result is considered as a direct evidence for the strong Pr 4f and P 3p hybridization effect on the unconventional ordered phase accompanied by the insulator state., Institute of Physics Publishing
Journal of Physics: Conference Series, Apr. 2018, [Reviewed]

Magnetic-ordering propagation vectors of terbium hexaboride revisited
Kazuaki Iwasa; Fumitoshi Iga; Taketo Moyoshi; Akiko Nakao; Takashi Ohhara, The magnetic ordered state of a single-crystal sample of TbB6 has been studied with the high-precision neutron diffraction instrument SENJU installed at BL18 of the Materials and Life Science Facility in J-PARC. We observed new Bragg reflection spots characterized by a propagation vector qM2 ¼ ð1=4
1=4
0Þ below the Néel temperature TN ≈ 20 K, in addition to qM1 ¼ ð1=4
1=4
1=2Þ reported in the literature. Because X-ray Thomson scattering measurements do not detect the qM2 superlattice reflections at 13 K, qM2 is a new magnetic-ordering propagation vector. The magnetic multi-q structure of TbB6 is similar to that of CeB6, whereas the ratio of the qM2 amplitude to that of qM1 is smaller than that in CeB6. The combination of qM1 and qM2 is expected to assist the qL1 ¼ ð1=2
0
0Þ lattice modulation., Physical Society of Japan
Journal of the Physical Society of Japan, 2018, [Reviewed]

Inelastic neutron scattering study on 4f-electron multipole system PrTr2X20 (Tr : transition metal, X : Al and Zn)
Kazuaki Iwasa; Takahiro Onimaru; Toshiro Takabatake; Ryuji Higashinaka; Yuji Aoki; Seiko Ohira-Kawamura; Kenji Nakajima, Lead, We have conducted inelastic neutron scattering measurements to investigate the crystal-electric-field (CEF) levels associated with Pr3+ 4f(2)-electron configuration in the PrTr2X20 (Tr: transition metal, X: Al and Zn). Hybridization between conduction electrons and 4f electrons has been deduced from the spectral widths, which is a key factor for understanding the anomalous low-temperature transport properties and the ordering phase transitions in the PrTr2X20. We also discuss structural-transition effects on local symmetries of the Pr-ion sites., ELSEVIER SCIENCE BV
Physica B: Physics of Condensed Matter, Nov. 2017, [Reviewed]

Magnetic Properties of Electron-Doped LaCoO3
Keisuke Tomiyasu; Mika Sato; Shun-Ichi Koyama; Tsutomu Nojima; Ryoichi Kajimoto; Sungdae Ji; Kazuaki Iwasa, We studied electron-doped LaCo1-yTey6+ O-3 by magnetization measurements and neutron scattering. The effective Bohr magneton, estimated by Curie-Weiss fitting around room temperature, is independent of y. This suggests that magnetic Co3+(HS), not nonmagnetic Co3+(LS), is mainly replaced by doped magnetic Co2+(HS). At the lowest temperatures, a Brillouin-function-like saturating behavior persists in the magnetization curves even in the high-y samples, and neither a clear magnetic reflection nor magnetic dispersion is observed by neutron scattering. These findings indicate that the magnetic correlation is very weak, in contrast to the well-known hole-doped LaCoO3 accompanied by a drastic transition to a ferromagnetic metal. However, we also found that the low-y samples exhibit nonnegligible enhancement of the saturated magnetization by similar to 2 mu(B) per a doped electron. All these characteristics are discussed in the light of the activation and inactivation of a spin-state blockade., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Sep. 2017, [Reviewed]

Crystal-electric-field excitations and spin dynamics in Ce3Co4Sn13 semimetallic chiral-lattice phase
Kazuaki Iwasa; Yuka Otomo; Kazuya Suyama; Keisuke Tomiyasu; Seiko Ohira-Kawamura; Kenji Nakajima; Jean-Michel Mignot, Inelastic neutron scattering experiments have been conducted to investigate the spin dynamics and crystal-electric- field level scheme of the Ce 4f electrons in Ce3Co4Sn13. This compound exhibits a large specific heat at low temperatures and anomalous semimetallic transport in the chiral crystallographic phase below 160 K. Distinctly observed magnetic excitations at approximately 6 and 29 meV are asymmetric in spectral shape and are reproduced by two inequivalent crystal-electric-field splitting schemes, which are deduced from the chiral structure. We have also observed the spin dynamics reflecting antiferromagnetic correlations below 1 meV, which is enhanced with an upturn in the electrical resistivity below 15 K and which yields a low-energy density of state relevant to the large specific heat. We discuss the possibility of a three-dimensional Weyl semimetal state, considering the chiral-lattice symmetry, electronic hybridization, and magnetic correlation., AMER PHYSICAL SOC
PHYSICAL REVIEW B, May 2017, [Reviewed]

Evidence for antiferromagnetic-type ordering of f -electron multipoles in PrIr2Zn20
Kazuaki Iwasa; Keisuke T. Matsumoto; Takahiro Onimaru; Toshiro Takabatake; Jean-Michel Mignot; Arsen Gukasov, Neutron diffraction measurements conducted under applied magnetic fields evidence the ordered structure of PrIr2Zn20 below approximately 0.1 K. A two-channel (orbital) Kondo effect is expected to act within the non-Kramers doublet ground state of the Pr 4f electrons of this material in cubic symmetry. Antiferromagnetic reflections are clearly induced under the influence of applied magnetic fields, which are characterized by the propagation vector q=(1/2,1/2,1/2). This result indicates antiferromagnetic-type ordering of the Pr f-electron multipoles. The Γ3-type quadrupole, O22, is the dominant order parameter deduced from the observed magnetic structure factor. We also discuss the entanglement of various finite-magnitude multipoles up to third rank, which are relevant to the low-energy crystalline-electric-field split levels in this material., American Physical Society
Physical Review B, Apr. 2017, [Reviewed]

Broad Excitation Spectra between Crystalline-Electric-Field Levels Associated with Non-Kramers Doublet Ground State of f Electrons in PrNb2Al20
Kazuaki Iwasa; Ryuji Higashinaka; Yuji Aoki; Seiko Ohira-Kawamura; Kenji Nakajima, Inelastic neutron scattering measurements of PrNb2Al20, which exhibits non-Fermi-liquid behaviors, were carried out in order to determine the f-electron crystalline-electric-field split. Magnetic inelastic scattering intensities were observed at excitation energies of up to 15 meV, which are attributed to the crystalline-electric-field level scheme with the non-Kramers Gamma(3) doublet ground state of 4 f(2) in Pr3+ ions. The intrinsic full width at half maximum of the excitations from Gamma(3) to Gamma(5) and Gamma(4) are estimated to be approximately 3.7 meV. These values are much larger than those of the isomorphic PrTr2Zn20 (Tr = Rh and Ir). The considerably broad spectrum of PrNb2Al20 supports the existence of hybridization between Pr 4f electrons and conduction electrons, which mediates the Kondo effect in this material., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Dec. 2016, [Reviewed]

Microscopic Examinations of Co Valences and Spin States in Electron-Doped LaCoO3
Keisuke Tomiyasu; Syun-Ichi Koyama; Masanori Watahiki; Mika Sato; Kazuki Nishihara; Yuki Takahashi; Mitsugi Onodera; Kazuaki Iwasa; Tsutomu Nojima; Hiroyuki Nojiri; Jun Okamoto; Di-Jing Huang; Yuuichi Yamasaki; Hironori Nakao; Youichi Murakami, We studied the Co valences and spin states in electron-doped LaCo1-yTeyO3 by measuring X-ray absorption spectra and electron spin resonance. The low-temperature insulating state involves the low-spin Co3+ state (S = 0) and the highspin Co2+ state, where the latter is described by g = 3.8 and j(eff) = 1/2. The results, in concurrence with the electron-hole asymmetry confirmed in the electrical resistivity, coincide with the spin-blockade phenomenon in this system. Furthermore, we discuss the g factor in terms of the strong covalent-bonding nature and consider multiple origins of this phenomenon., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Sep. 2016

Chiral crystal-structure transformation of R3Co4Sn13 (R = La and Ce)
Yuka Otomo; Kazuaki Iwasa; Kazuya Suyama; Keisuke Tomiyasu; Hajime Sagayama; Ryoko Sagayama; Hironori Nakao; Reiji Kumai; Youichi Murakami, The compounds designated as R3T4Sn13 (R = rare earth and T = transition metal) are hypothesized to be strongly correlated electron systems. Some of these compounds exhibit structural phase transitions with speculated charge-density-wave (CDW) formations. We carried out x-ray diffraction measurements in order to investigate the second-order phase transition of R3Co4Sn13 (R = La and Ce) by using single-crystalline samples synthesized by the molten Sn-flux method. Both compounds exhibit the structural superlattice transformations characterized by the wave vector q = (1/2,1/2,0) below T-D similar or equal to 160 K, which originate from electronic states owing to the common Co and Sn. The space group of the low-temperature phase is evidenced as a chiral cubic I2(1)3. The magnetic-susceptibility enhancement and the Co-ion valence shift below T-D are signatures of a phase transition not fully attributed to the conventional CDW formation., AMER PHYSICAL SOC
PHYSICAL REVIEW B, Aug. 2016

Second-order structural transition in the superconductor La3Co4Sn13
Y. W. Cheung; J. Z. Zhang; J. Y. Zhu; W. C. Yu; Y. J. Hu; D. G. Wang; Yuka Otomo; Kazuaki Iwasa; Koji Kaneko; Masaki Imai; Hibiki Kanagawa; Kazuyoshi Yoshimura; Swee K. Goh, The quasiskutterudite superconductor La3Co4Sn13 undergoes a phase transition at T* = 152 K. By measuring the temperature dependence of heat capacity, electrical resistivity, and the superlattice reflection intensity using x rays, we explore the character of the phase transition at T*. Our lattice dynamic calculations found imaginary phonon frequencies around the M point when the high-temperature structure is used in the calculations, indicating that the structure is unstable at the zero-temperature limit. The combined experimental and computational results establish that T* is associated with a second-order structural transition with q = (0.5,0.5,0) (or the M point). Further electronic band structure calculations reveal Fermi surface sheets with low-curvature segments, which allow us to draw qualitative comparison with both Sr3Ir4Sn13 and Sr3Rh4Sn13 in which similar physics has been discussed recently., AMER PHYSICAL SOC
PHYSICAL REVIEW B, Jun. 2016

20pPSB-30 Powder neutron diffraction of valence ordering compound YbPd
Oyama K.; Mitsuda A.; Ohoyama K.; Matsukawa T.; Yoshida Y.; Hoshikawa A.; Ishigaki T.; Iwasa K.; Wada H., The Physical Society of Japan (JPS)
Meeting Abstracts of the Physical Society of Japan, 2016

22aPS-36 Excited states of NdT_4P_<12> (T = Fe, Ru) observed by inelastic neutron scattering
Iwasa K.; Itoh S.; Yokoo T.; Ibuka S.; Sekine C.; Sugawara H., The Physical Society of Japan (JPS)
Meeting Abstracts of the Physical Society of Japan, 2016

Inelastic neutron scattering study on magnetic excitation in Ce_0.7La_0.3B₆
Oguri S.; Kaiki R.; Kuwahara K.; Iga F.; Iwasa K.; Kaneko K.; Shiina R.; Kawamura S.; Nakajima N.; Yokoo T.; Itoh S.,

Ce_0.7_La_0.3_B_6_の反強八極子秩序状態での低エネルギー磁気励起を微視的に調べるため、単結晶試料の極低温非弾性中性子散乱実験をJ-PARCで行なった。反強八極子秩序状態での揺らぎは、これまでに報告されているCeB_6_の反強四極子秩序及び反強磁性秩序での磁気揺らぎとは異なっていることがわかった。その結果について報告する。

, The Physical Society of Japan
Meeting Abstracts of the Physical Society of Japan, 2016

Polarisation Analysis Neutron Spectrometer, POLANO, at J-PARC- Concept and Magnetic Field Optimisation
K. Ohoyama; T. Yokoo; S. Itoh; M. Nanbu; K. Iwasa; M. Ohkawara; N. Kaneko; T. Ino; H. Hayashida; T. Oku; H. Kira; S. Tasaki; M. Takeda; H. Kimura; T. J. Sato, The status of the polarised neutron spectrometer constructed at the Japan Proton Accelerator Research Complex through a collaboration between Tohoku University and KEK will be reported. In particular, the optimisation of magnetic fields to minimise neutron beam depolarisation using the finite element method will be discussed on the basis of several simulations using the finite element method.., IOP PUBLISHING LTD
INTERNATIONAL CONFERENCE ON POLARISED NEUTRONS FOR CONDENSED MATTER INVESTIGATIONS (PNCMI 2014), 2016, [Reviewed]

Magnetic and electronic states in (LaMnO3)(2)(SrMnO3)(2) superlattice exhibiting a large negative magnetoresistance
Hironori Nakao; Takaaki Sudayama; Masato Kubota; Jun Okamoto; Yuichi Yamasaki; Youichi Murakami; Hiroyuki Yamada; Akihito Sawa; Kazuaki Iwasa, Magnetic and electronic states in (LaMnO3)(2)(SrMnO3)(2) superlattices fabricated on an (LaAlO3)(0.3)(SrAl0.5Ta0.5O3)(0.7) substrate, which exhibit a large nontrivial negative magnetoresistance (MR) effect, have been investigated. The crystal structure and the Mn valence state were determined using x-ray scattering measurements near the Mn K edge. These measurements revealed that the Mn valences in the LaMnO3 and SrMnO3 layers are 3+ and 4+, respectively; that is, valence modulation coincides with the La/Sr stacking structure. The Mn spin structure was studied by means of resonant soft x-ray scattering at the Mn L-2,L-3 edge and neutron magnetic scattering measurements. We succeeded in detecting a magnetic signal indicating ferromagnetism at the interface. Finally, we suggest that the origin of the MR is the competition between ferromagnetism at the interface and underlying antiferromagnetism., AMER PHYSICAL SOC
PHYSICAL REVIEW B, Dec. 2015, [Reviewed]

Science from the Initial Operation of HRC
Shinichi Itoh; Tetsuya Yokoo; Takatsugu Masuda; Hideki Yoshizawa; Minoru Soda; Yoichi Ikeda; Soshi Ibuka; Daichi Kawana; Taku J. Sato; Yusuke Nambu; Keitaro Kuwahara; Shin-ichiro Yano; Jun Akimitsu; Yoshio Kaneko; Yoshinori Tokura; Masaki Fujita; Masashi Hase; Kazuaki Iwasa; Haruhiro Hiraka; Tatsuo Fukuda; Kazuhiko Ikeuchi; Koji Yoshida; Toshio Yamaguchi; Kanta Ono; Yasuo Endoh, Journal of the Physical Society of Japan
JPS Conf. Proc., Sep. 2015, [Reviewed]

19pDC-2 Characterization of spin-state molecular magnets in LaCoO_3 with light Ni substitution
Sinaga Evelyn; Tomiyasu Keisuke; Iwasa Kazuaki; Nojima Tsutomu; Nakao Hironori; Murakami Youichi, The Physical Society of Japan (JPS)
Meeting Abstracts of the Physical Society of Japan, 2015

18pDA-8 Neutron diffraction study on multipole ordering in PrIr_2Zn_<20>
Iwasa K.; Matsumoto K. T.; Onimaru T.; Takabatake T.; Mignot J.-M.; Meuriot J.-L.; Gukasov A., The Physical Society of Japan (JPS)
Meeting Abstracts of the Physical Society of Japan, 2015

17aPS-21 Single-crystal structural analysis of R_3Co_4Sn_<13>(R=Ce and La) by using synchrotron X-ray diffraction
Otomo Y.; Suyama K.; Iwasa K.; Tomiyasu K.; Sagayama H.; Sagayama R.; Nakao H.; Kumai R.; Murakami Y., The Physical Society of Japan (JPS)
Meeting Abstracts of the Physical Society of Japan, 2015

17aPS-22 Structural phase transitions of R_3Rh_4Sn_<13>(R=Ce, La)
Suyama K.; Otomo Y.; Iwasa K.; Tomiyasu K.; Nakao H.; Sagayama H.; Sagayama R.; Kumai R.; Murakami Y., The Physical Society of Japan (JPS)
Meeting Abstracts of the Physical Society of Japan, 2015

22aBC-5 Spin-state blockade in Te^<6+>-substitution electron-doped LaCoO_3
Tomiyasu K.; Koyama S.; Watahiki M.; Sato M.; Nishihara K.; Onodera M.; Iwasa K.; Nojima T.; Yamasaki Y.; Nakao H.; Murakami Y., The Physical Society of Japan (JPS)
Meeting Abstracts of the Physical Society of Japan, 2015

21pBB-11 Nd-ion substitution effect on f-electron multipole order in PrRu_4P_<12>
Iwasa K.; Yonemoto A.; Takagi S.; Itoh S.; Yokoo T.; Ibuka S.; Sekine C.; Sugawara H., The Physical Society of Japan (JPS)
Meeting Abstracts of the Physical Society of Japan, 2015

Polarized neutron spectrometer for inelastic experiments at J-PARC Status of POLANO Project
Tetsuya Yokoo; Kenji Ohoyama; Shinichi Itoh; Kazuaki Iwasa; Naokatsu Kaneko; Junichi Suzuki; Manabu Ohkawara; Kazuya Aizawa; Seiji Tasaki; Takashi Ino; Kaoru Taketani; Shigeru Ishimoto; Masayasu Takeda; Takayuki Oku; Hiroshi Kira; Kouichi Hayashi; Hiroyuki Kimura; Taku J. Sato, Construction of the newly developed polarization analysis neutron chopper spectrometer (POLANO) commenced in the Japan Proton Accelerator Research Complex (J-PARC), Materials and Life Science Experimental Facility (MLF). The POLANO is a direct geometry chopper spectrometer with neutron polarization analysis capability. In the suite of inelastic spectrometers, six instruments are now in operation. POLANO will be the only spectrometer dedicated to polarization analysis experiments. The primary phase of the construction will be completed by 2014 with beam commissioning scheduled for 2015., E D P SCIENCES
QENS/WINS 2014 - 11TH INTERNATIONAL CONFERENCE ON QUASIELASTIC NEUTRON SCATTERING AND 6TH INTERNATIONAL WORKSHOP ON INELASTIC NEUTRON SPECTROMETERS, 2015, [Reviewed]

Nd-ion substitution effect on f-electron multipole order of PrRu4P12
Kazuaki Iwasa; Ari Yonemoto; Shigeru Takagi; Shinichi Itoh; Tetsuya Yokoo; Soshi Ibuka; Chihiro Sekine; Hitoshi Sugawara, We studied the effect of magnetic Nd-ion substitution on the metal-nonmetal transition at a transition temperature of 63 K of PrRu4P12, which is characterized by antiferro-type electric multipole ordering of Pr-ion 4f electrons. The transition temperature of Pr1-xNdxRu4P12 depends weakly on the Nd concentration x as compared to La-and Ce-substituted compounds. Inelastic neutron-scattering measurements revealed that the energies and widths of crystalline field excitation peaks of Pr 4f(2) in Pr0.85Nd0.15Ru4P12 are very similar to those of PrRu4P12. These experimental results indicate that the ordered state is robust against the substitution of magnetic Nd ions as compared to the La and Ce substitutions. Magnetic interactions between the Pr ions and the Nd ions in Pr1-xNdxRu4P12 help stabilize the magnetic triplet ground state of the Pr ions that appears in the antiferro-type multipole ordered phase. Therefore, the nonmagnetic multipole ordered phase of PrRu4P12 is compatible with the magnetic perturbation., ELSEVIER SCIENCE BV
20TH INTERNATIONAL CONFERENCE ON MAGNETISM, ICM 2015, 2015

Spin-Orbit Fluctuations in Frustrated Heavy-Fermion Metal LiV2O4
K. Tomiyasu; K. Iwasa; H. Ueda; S. Niitaka; H. Takagi; S. Ohira-Kawamura; T. Kikuchi; Y. Inamura; K. Nakajima; K. Yamada, Spin fluctuations were studied over a wide momentum ((h) over barQ) and energy (E) space in the frustrated d-electron heavy-fermion metal LiV2O4 by time-of-flight inelastic neutron scattering. We observed the overall Q - E evolutions near the characteristic Q = 0.6 angstrom(-1) peak and found another weak broad magnetic peak around 2.4 angstrom(-1). The data are described by a simple response function, a partially delocalized magnetic form factor, and antiferromagnetic short-range spatial correlations, indicating that heavy-fermion formation is attributable to spin-orbit fluctuations with orbital hybridization., AMER PHYSICAL SOC
PHYSICAL REVIEW LETTERS, Dec. 2014, [Reviewed]

Universality of Anharmonic Motion of Heavy Rare-Earth Atoms in Hexaborides
Iwasa Kazuaki; Iga Fumitoshi; Yonemoto Ari; Otomo Yuka; Tsutsui Satoshi; Baron Alfred Q. R., Lead, Phonons of TbB₆are studied by inelastic X-ray scattering and compared with those of GdB₆and DyB₆. Measured low-lying phonon modes located near 6 meV soften distinctly with decreasing temperature, particularly the longitudinal phonon that is dominated by the motion of Tb ions at . The magnitude and temperature dependence of phonon energy are between those of GdB₆and DyB₆. We derive a Landau-type free-energy expansion with respect to the atomic displacement in TbB₆, and discuss a general feature among these three compounds. The systematic variation in the phonon characteristics of these hexaborides and the first-order-like instability indicate the universality of the anharmonic motion of heavy rare-earth atoms in RB₆(R= Gd, Tb, and Dy)., The Physical Society of Japan
Journal of the Physical Society of Japan, Aug. 2014, [Reviewed]

Emergence of reentrant metal-nonmetal transition in Pr0.85Ce0.15Ru4P12 and Pr(Ru0.95Rh0.05)(4)P-12
Kotaro Saito; Claire Laulhe; Takahiro Sato; Lijie Hao; Jean-Michel Mignot; Kazuaki Iwasa, The metal-nonmetal transition in Ce- and Rh-substituted PrRu4P12 was investigated through magnetic susceptibility, x-ray superlattice reflection, and inelastic neutron scattering (INS) measurements. The saturation in the magnetic susceptibility at low temperatures suggests a singlet ground state for Pr sites in both compounds. This finding is in contrast to the staggered order of singlet and triplet ground states found in the ordered phase of PrRu4P12, which leads to a diverging susceptibility. The intensities of x-ray superlattice reflections of both compounds develop below 45 K and decrease rapidly below 10 K with a simultaneous decrease in electrical resistivity. INS experiments reveal that 4f electron states in both compounds change drastically from two distinct crystal field (CF) level schemes corresponding to an order parameter in the multipole ordered phase (10 K < T < 45 K) to a nearly uniform CF level scheme below 10 K. The uniform CF ground state at the Pr sites carries no degree of freedom relevant to the staggered ordering pattern and electronic gap formation. Therefore, the substituted systems exhibit a reentrant metallic state at the lowest temperature. These phenomena may originate from effective electron doping due to atomic substitution., AMER PHYSICAL SOC
PHYSICAL REVIEW B, Feb. 2014, [Reviewed]

Construction of Polarized Inelastic Neutron Spectrometer in J-PARC
T. Yokoo; K. Ohoyama; S. Itoh; J. Suzuki; M. Nanbu; N. Kaneko; K. Iwasa; T. J. Sato; H. Kimura; M. Ohkawara, The instrumental design of the Polarization Analysis Neutron Spectrometer with Correlation Method (POLANO) is almost ready for its construction, although some discussion on the design still remains. POLANO is a new inelastic neutron spectrometer in the Japan Proton Accelerator Research Complex (J-PARC) utilizing polarized neutrons for comprehensive materials research, focusing on the use of quasi-elastic and inelastic scattering techniques. For instrumental construction, the basic shield design is complete and the shielding capability against radiation has been assessed. Additionally, the designs of the beam transport section using 4 Q(c) supermirror guide tube are almost complete. Also, detecting section and a large vacuum chamber is now under designing. The development of polarization and chopper devices are the key to the success for the very first application of polarization analysis to inelastic scattering at spallation neutron source. High performance Fermi and T0 choppers are now under manufacturing., IOP PUBLISHING LTD
1ST CONFERENCE ON LIGHT AND PARTICLE BEAMS IN MATERIALS SCIENCE 2013 (LPBMS2013), 2014, [Reviewed]

Concepts of Neutron Polarisation Analysis Devices for a New Neutron Chopper Spectrometer, POLANO, in J-PARC
K. Ohoyama; T. Yokoo; S. Itoh; T. Ino; M. Ohkawara; T. Oku; S. Tasaki; K. Iwasa; T. J. Sato; S. Ishimoto; K. Taketani; H. Kira; Y. Sakaguch; M. Nanbu; H. Hiraka; H. M. Shimizu; M. Takeda; M. Hino; K. Hayashi; U. Fliges; P. Hautle, The basic concept of polarisation analysers with bender type supermirrors on the polarised neutron spectrometer, POLANO, which is now under construction in J-PARC/MLF, is described, IOP PUBLISHING LTD
1ST CONFERENCE ON LIGHT AND PARTICLE BEAMS IN MATERIALS SCIENCE 2013 (LPBMS2013), 2014, [Reviewed]

Well-Defined Crystal Field Splitting Schemes and Non-Kramers Doublet Ground States of f Electrons in PrT_{2}Zn
Iwasa Kazuaki; Kobayashi Hiroki; Onimaru Takahiro; Matsumoto Keisuke T.; Nagasawa Naohiro; Takabatake Toshiro; Ohira-Kawamura Seiko; Kikuchi Tatsuya; Inamura Yasuhiro; Nakajima Kenji, Lead, Inelastic neutron scattering studies of PrT_{2}Zn20(T = Ir, Rh, and Ru) were carried out in order to reveal f electron states indispensable for the low-temperature properties of PrT_{2}Zn20associated with multipole degrees of freedom. Sharp excitation peaks, which are located within excitation energies of less than 10 meV, are attributed to crystal field splitting level schemes of 4f^{2} in Pr³⁺ions. Data of the Ir-based compound is explained by a non-Kramers doublet ground state in the local symmetry T_{d} for this system. Results of the Rh-based compound are explained by the scheme for the Pr-site local cubic symmetry T in the low-temperature structural phase, which is lower than T_{d}. In the Ru-based compound, the doublet is split as a result of the loss of local cubic symmetry through structural transformation. These experimental results confirm the non-Kramers doublet ground state that causes the quadrupole ordering or orbital Kondo effect predicted for this series of compounds., The Physical Society of Japan
J Phys Soc Jpn, Apr. 2013, [Reviewed]

Well-Defined Crystal Field Splitting Schemes and Non-Kramers Doublet Ground States of f Electrons in PrT2Zn20 (T = Ir, Rh, and Ru)
Iwasa, Kazuaki; Kobayashi, Hiroki; Onimaru, Takahiro; Matsumoto, Keisuke T; Nagasawa, Naohiro; Takabatake, Toshiro; Ohira-Kawamura, Seiko; Kikuchi, Tatsuya; Inamura, Yasuhiro; Nakajima, Kenji, Inelastic neutron scattering studies of PrT2Zn20 (T = Ir, Rh, and Ru) were carried out in order to reveal f electron states indispensable for the low-temperature properties of PrT2Zn20 associated with multipole degrees of freedom. Sharp excitation peaks, which are located within excitation energies of less than 10 meV, are attributed to crystal field splitting level schemes of 4f(2) in Pr3+ ions. Data of the Ir-based compound is explained by a non-Kramers doublet ground state in the local symmetry T-d for this system. Results of the Rh-based compound are explained by the scheme for the Pr-site local cubic symmetry T in the low-temperature structural phase, which is lower than T-d. In the Ru-based compound, the doublet is split as a result of the loss of local cubic symmetry through structural transformation. These experimental results confirm the non-Kramers doublet ground state that causes the quadrupole ordering or orbital Kondo effect predicted for this series of compounds., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Apr. 2013, [Reviewed]

26aXZB-2 Progress of Polarisation Analysis Neutron Spectrometer Project in J-PARC
Ohoyama K; Yokoo T; Itoh S; Suzuki J; Sato T. J; Iwasa K; Kira H; Sakaguchi Y; Oku T; Ino T; Hiraka H; Matsuura M; Fujita M; Tomiyasu K; Kimura H; Suzuki J; Shimizu H. M; Arima T; Takeda M; Kaneko K; Hino M; Muto S; Nojiri H; Lee C. H; Park J. G; Choi S, 一般社団法人日本物理学会
Meeting abstracts of the Physical Society of Japan, Mar. 2013

Growth of single crystal and effects of electron doping in filled skutterudite compound PrFe₄P₁₂
Hao, L.J.; Iwasa, K.; Liu, R.D.; Ma, X.B.; Liu, Z.X.; Li, S.L.; Hu, D.; Liu, Y.T.; Chen, D.F., Advanced Materials Research
Advanced Materials Research, 2013

26aXZB-2 J-PARC偏極中性子散乱装置POLANO計画の状況(26aXZB 領域10,ビーム物理領域合同 X線・粒子線(中性子),領域10(誘電体,格子欠陥,X線・粒子線,フォノン))
大山 研司; 横尾 哲也; 伊藤 晋一; 鈴木 純一; 佐藤 卓; 岩佐 和晃; 吉良 弘; 坂口 佳史; 奥 隆之; 猪野 隆; 平賀 晴弘; 松浦 直人; 藤田 全基; 富安 啓輔; 木村 宏之; 鈴木 淳市; 清水 裕彦; 有馬 孝尚; 武田 全康; 金子 耕士; 日野 正裕; 武藤 豪; 野尻 浩之; C. H. Lee; J. G. Park; S. Choi, 一般社団法人日本物理学会
日本物理学会講演概要集, Jan. 2013

Basic Concepts of Polarisation Analysis for Neutron Chopper Spectrometer POLANO at J-PARC
K. Ohoyama; T. Yokoo; S. Itoh; J. Suzuki; K. Iwasa; T. J. Sato; H. Kira; Y. Sakaguchi; T. Ino; T. Oku; K. Tomiyasu; M. Matsuura; H. Hiraka; M. Fujita; H. Kimura; T. Sato; J. Suzuki; H. M. Shimizu; T. Arima; M. Takeda; K. Kaneko; M. Hino; S. Muto; H. Nojiri; C. H. Lee; J. G. Park; S. Choi, Physical Society of Japan
Journal of the Physical Society of Japan, 2013, [Reviewed]

Successive phase transitions induced by magnetic fields in a cubic system, NdPd₃S₄
M. Watahiki; E. Matsuoka; K. Iwasa; Y. Matsumoto; S. Nakamura; T. Nojima; K. Ohoyama; K. Tanigaki; H. Aoki; H. Onodera
Journal of Physics: Conference Series, Dec. 2012, [Reviewed]

Renormalized Motion of Dysprosium Atoms Filling Boron Cages of DyB6
Kazuaki Iwasa; Keitaro Kuwahara; Yoshihiro Utsumi; Kotaro Saito; Hiroki Kobayashi; Takahiro Sato; Mitsuhide Amano; Takumi Hasegawa; Norio Ogita; Masayuki Udagawa; Satoshi Tsutsui; Alfred Q. R. Baron, The lattice dynamics of DyB6 are investigated by an inelastic X-ray scattering technique. The measured phonon modes are dominated by the motion of Dy ions in oversized boron cages. These soften remarkably as temperature is decreased, with the energy of the longitudinal phonon for the propagation vector q(1) = (1/2, 0, 0) decreasing by 29% from 300 K down to the phase transition temperature of 31 K. The dispersion relation curves show kinklike anomalies at q(k) = (0.38, 0.38, 0). The observed phenomena are very similar to those previously observed in GdB6 [Iwasa et al.: Phys. Rev. B 84 (2011) 214308]. We note analogous phonon anomalies in the heavier rare-earth hexaboride systems, owing to the interplay between the motion of rare-earth atoms and the electronic state, particularly characterized by the Friedel oscillation., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Nov. 2012

Newly Proposed Inelastic Neutron Spectrometer POLANO　　　　　　　　　　　　　　　
Tetsuya Yokoo; Kenji Ohoyama; Shinichi Itoh; Junichi Suzuki; Kazuaki Iwasa; Taku J Sato; Hiroshi Kira; Yoshifumi Sakaguchi; Takashi Ino; Takayuki Oku; Keisuke Tomiyasu; Masato Matsuura; Haruhiro Hiraka; Masaki Fujita; Hiroyuki Kimura; Toyoto Sato; Junichi Suzuki; Masayasu Takeda; Koji Kaneko; Masahiro Hino; Suguru Muto
Journal of the Physical Society of Japan, Sep. 2012, [Reviewed]

Magnetic excitation in totally symmetric staggered ordered phase of PrFe 4P 12
Kazuaki Iwasa; Lijie Hao; Masahumi Kohgi; Keitaro Kuwahara; Jean-Michel Mignot; Hitoshi Sugawara; Yuji Aoki; Tatsuma D. Matsuda; Hideyuki Sato, We report inelastic neutron scattering results for single-crystalline samples of PrFe4P12, which undergoes a transition from the heavy-electron phase to the antiferro-type nonmagnetic ordered phase. In contrast to the quasielastic magnetic response observed in the heavy electron phase, the well-defined inelastic peaks located at 1.5 and 3meV are superimposed in the ordered phase. The maximum spectral intensity appears at the Brillouin zone center for the original Im3̄ structure, and the minimum spectral intensity appears at the zone boundaries including the ordering vector q 0 = (1,0.0). The evolution of the 1.5 meV peak with an applied magnetic field in the ordered phase is in agreement with excitations between 4f-electron crystalline-field- splitting levels, while the 3 meV peak is smeared out rapidly. The spectra are consistent with the recently proposed staggered ordering of a Pr site with well-localized f-electrons and that with a Kondo-singlet-like state, which are represented as the totally symmetric state accompanied by the charge modulation of carriers. © 2012 The Physical Society of Japan., The Physical Society of Japan
Journal of the Physical Society of Japan, Sep. 2012

Modified cross-correlation for efficient white-beam inelastic neutron scattering spectroscopy
Tomiyasu, K.; Matsuura, M.; Kimura, H.; Iwasa, K.; Ohoyama, K.; Yokoo, T.; Itoh, S.; Kudoh, E.; Sato, T.; Fujita, M.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Jun. 2012, [Reviewed]

Emergence of Magnetic Long-range Order in Frustrated Pyrochlore Nd2Ir2O7 with Metal-Insulator Transition
Keisuke Tomiyasu; Kazuyuki Matsuhira; Kazuaki Iwasa; Masanori Watahiki; Seishi Takagi; Makoto Wakeshima; Yukio Hinatsu; Makoto Yokoyama; Kenji Ohoyama; Kazuyoshi Yamada, In this study, we performed powder neutron diffraction and inelastic scattering measurements of frustrated pyrochlore Nd2Ir2O7, which exhibits a metal-insulator transition at a temperature T-MI of 33 K. The diffraction measurements revealed that the pyrochlore has an antiferromagnetic long-range structure with propagation vector q(0) of (0, 0, 0) and that it grows with decreasing temperature below 15 K. This structure was analyzed to be of the all-in all-out type, consisting of highly anisotropic Nd3+ magnetic moments of magnitude 2.3 +/- 0.4 mu(B), where mu(B) is the Bohr magneton. The inelastic scattering measurements revealed that the Kramers ground doublet of Nd3+ splits below T-MI. This suggests the appearance of a static internal magnetic field at the Nd sites, which probably originates from a magnetic order consisting of Ir4+ magnetic moments. Here, we discuss a magnetic structure model for the Ir order and the relation of the order to the metal-insulator transition in terms of frustration., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Mar. 2012

Magnetic Phase Diagrams of YVO3 and TbVO3 under High Pressure
Daisuke Bizen; Hironori Nakao; Kazuaki Iwasa; Youichi Murakami; Toyotaka Osakabe; Jun Fujioka; Toshio Yasue; Shigeki Miyasaka; Yoshinori Tokura, Magnetic states in RVO3 (R = Y, Tb) were investigated using low-temperature and high-pressure neutron-diffraction techniques, and the pressure-temperature magnetic phase diagrams were clarified up to 6.2 GPa. We elucidated that, on application of pressure, the magnetic ground state changes from C-type spin ordering (C-SO) to G-type spin ordering (G-SO); this corresponds to the orbital ground-state switching from G-type orbital ordering (G-OO) to C-type orbital ordering (C-OO). It is also interesting that the G-SO transition occurs simultaneously with the C-OO transition, but not with the G-OO one. When the transition temperature of C-OO exceeds that of G-OO under high pressure, the G-OO phase vanishes completely, and a simultaneous spin and orbital order-disorder phase transition occurs. Such a transition is the first case in perovskite-type transition-metal oxides., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Feb. 2012

Neutron scattering study on magnetic ordering in a partially rare-earth filled skutterudite Prx Fe4 Sb12
K Iwasa; T Orihara; K Saito; K Tomiyasu; Y Murakami; H Sugawara; K Kuwahara; H Kimura; R Kiyanagi; Y Ishikawa; Y Noda; Y Aoki; H Sato; M Kohgi
Journal of Physics: Conference Series, 2012, [Reviewed]

Motion of the guest ion as precursor to the first-order phase transition in the cage system GdB 6
Kazuaki Iwasa; Ryosuke Igarashi; Kotaro Saito; Claire Laulhé; Toshihiko Orihara; Satoru Kunii; Keitaro Kuwahara; Hironori Nakao; Youichi Murakami; Fumitoshi Iga; Masafumi Sera; Satoshi Tsutsui; Hiroshi Uchiyama; Alfred Q. R. Baron, The motion of guest Gd ions in oversized boron cages in GdB 6 was investigated from phonon spectra measurements obtained by inelastic x-ray scattering. The measured phonon modes soften by about 10% from 300 K down to T N=16 K, in particular, the longitudinal phonon for the propagation vector q 1=(1/2,0,0) that characterizes the distorted structure below T N. Besides, the dispersion relation curves show kinklike anomalies at q k=(0.38,0.38,0). The observed results imply that the motion of the guest Gd ion interplays with the f electrons magnetoelastically and with carriers via Fermi surface nesting. The anomalous properties previously reported for this material far above T N originate from the strong electron-phonon coupling, which causes the motion of guest ions as precursors to the first-order phase transition. © 2011 American Physical Society.
Physical Review B - Condensed Matter and Materials Physics, Dec. 2011, [Reviewed]

Motion of the guest ion as precursor to the first-order phase transition in the cage system GdB6
Iwasa Kazuaki; Igarashi Ryosuke; Saito Kotaro; Laulhe Claire; Orihara Toshihiko; Kunii Satoru; Kuwahara Keitaro; Nakao Hironori; Murakami Youichi; Iga Fumitoshi; Sera Masafumi; Tsutsui Satoshi; Uchiyama Hiroshi; Baron Alfred Q. R
PHYSICAL REVIEW B, Dec. 2011, [Reviewed]

Effects of cation-size variance on spin and orbital orders in Eu 1-x(La0.254Y0.746)xVO3
R. Fukuta; S. Miyasaka; K. Hemmi; S. Tajima; D. Kawana; K. Ikeuchi; Y. Yamasaki; A. Nakao; H. Nakao; Y. Murakami; K. Iwasa, We have investigated the R-ion (R = rare earth or Y) size variance effect on spin/orbital order in Eu1-x(La0.254Y 0.746)xVO3. The size variance disturbs one-dimensional orbital correlation in C-type spin/G-type orbital ordered states and suppresses this spin/orbital order. In contrast, it stabilizes the other spin/orbital order. The results of neutron and resonant x-ray scattering denote that in the other ordered phase, the spin/orbital patterns are G type/C type, respectively. © 2011 American Physical Society.
Physical Review B - Condensed Matter and Materials Physics, Oct. 2011

Molecular spin-orbit excitations in the J(eff)=1/2 frustrated spinel GeCo2O4
K. Tomiyasu; M. K. Crawford; D. T. Adroja; P. Manuel; A. Tominaga; S. Hara; H. Sato; T. Watanabe; S. I. Ikeda; J. W. Lynn; K. Iwasa; K. Yamada, We describe powder and single-crystal inelastic neutron scattering experiments on a spinel-type antiferromagnet GeCo2O4, represented by an effective total angular momentum J(eff) = 1/2. Several types of nondispersive short-range magnetic excitations were discovered. The scattering intensity maps in Q space are well reproduced by dynamical structure factor analyses using molecular model Hamiltonians. The results of analyses suggest that the molecular excitations below T-N arise from molecular ground states, one of which consists of antiferromagnetically coupled ferromagnetic subunits. The quasielastic excitations above T-N are interpreted as its precursor. A combination of frustration and J(eff) = 1/2 might induce these quantum phenomena., AMER PHYSICAL SOC
PHYSICAL REVIEW B, Aug. 2011, [Reviewed]

Softening of phonon by filled rare-earth ion motion common to skutterudite with Sb cages
Kazuaki Iwasa; Yoshiaki Mori; Shohei Itobe; Ryosuke Igarashi; Youichi Murakami; Hitoshi Sugawara; Masahumi Kohgi; Hideyuki Sato, We investigate phonon modes of the rare-earth filled skutterudite compounds CeRu4Sb12, CeOs4Sb12, PrRu4Sb12, and PrOs4Sb12 by using an inelastic neutron scattering technique. These materials exhibit similar low-lying motions of filled ions inside the Sb cages that softens with decreasing temperature. Potentials at the rare-earth sites are considerably anharmonic. Despite that this behavior appears in all the four materials, magnitude of the softening of PrOs4Sb12 is largest among them. This fact implies that difference of carrier state gives rise to renormalization effect on the rare-earth-ion vibrations., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Jul. 2011

Magnetic Field and Temperature Dependence of X-ray Superlattice Intensity in Multipole Ordered Phase of Pr(Ru1-xRhx)(4)P-12 (x=0, 0.03)
Kotaro Saito; Kazuaki Iwasa; Lijie Hao; Hironori Nakao; Youichi Murakami, Superlattice reflections in the multipole ordered phase of PrRu4P12 and Pr(Ru0.97Rh0.03)(4)P-12 has been measured using a synchrotron x-ray scattering technique. The Thomson scattering intensity of (111) at 1.7 K does not show significant variation with magnetic field up to 7 T in contrast to the reported variation of electrical resistivity. This means that the lattice distortion in the ordered phase is robust and the staggered ordering remains after split of triplet ground state at half of Pr sites. The nonmetallic staggered ordering is not destroyed completely by applying magnetic field. Energy scan at (111) reflection of Pr(Ru0.97Rh0.03)(4)P-12 show temperature dependence around resonant energy of Pr L-3 edge. This may allow us to observe anisotropy of electronic ordering of Pr sites and gives us a hint for direct observation of higher rank multipole order in PrRu4P12., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Jul. 2011

Softening of the Longitudinal Phonon Mode along the [100] Direction in GdB6
K. Iwasa; R. Igarashi; K. Saito; C. Laulhe; T. Orihara; S. Kunii; K. Kuwahara; H. Nakao; Y. Murakami; F. Iga; M. Sera; S. Tsutsui; H. Uchiyama; A. Q. R. Baron, We have investigated the phonon of GdB6, which exhibits antiferromagnetic and structural first-order phase transition by using the inelastic x-ray scattering technique. The dispersion relation curve of the longitudinal acoustic mode propagating along the simple cubic [100] axis shows the maximum energy around the wave vector q = xi, 0, 0), xi = 0.2 - 0.3, and it bends clown with approaching the Brillouin zone boundary. The lower-energy zone-boundary mode at q(1) = (1/2, 0, 0) corresponds to the structural modulation in the ordered phase. The energy of this mode is 75% of the maximum value on the branch at 300 K and further decreases by 10% with decreasing temperature down to the transition temperature T-N = 16 K so that this phonon mode softens considerably far above the transition temperature. On the other hand, the reference material YbB6 that is considered to have no localized magnetic moments does not show such softening in the inelastic neutron scattering measurement. The observation indicates a strong electron-phonon coupling in GdB6, which is expected to be magnetoelastic-type interaction between 4f states and displacement of Gd ions., ELSEVIER SCIENCE BV
CHINESE JOURNAL OF PHYSICS, Feb. 2011, [Reviewed]

Crystalline electric field study in the pyrochlore Nd(2)Ir(2)O(7) with metal-insulator transition
M. Watahiki; K. Tomiyasu; K. Matsuhira; K. Iwasa; M. Yokoyama; S. Takagi; M. Wakeshima; Y. Hinatsu, We carried out inelastic neutron scattering measurements to identify crystalline electric field (CEF) states of Nd(3+) (a total angular momentum J = 9/2) in Nd(2)Ir(2)O(7), which exhibits a metal-insulator transition at T(MI) = 36 K. Excitation peaks observed around 26 and 41 meV are interpreted as CEF excitations within five Kramers doublets. It is notable that splitting of the ground doublet by 1.3 meV was microscopically observed at 3 K for the first time, indicating emergence of magnetic long-range order despite geometrical frustration. The splitting width decreases with increasing the temperature towards T(MI) like an order parameter of the transition. We discuss the results in light of Nd-Ir interactions., IOP PUBLISHING LTD
INTERNATIONAL CONFERENCE ON FRUSTRATION IN CONDENSED MATTER (ICFCM), 2011, [Reviewed]

Neutron scattering study of spiral-type spin correlations in the frustrated spinel Mn0.07Mg0.93Cr2O4
T. Yokobori; K. Tomiyasu; Y. Kousaka; H. Matsui; H. Hiraka; K. Iwasa; K. Yamada; J. Akimitsu, We studied spiral-type spin correlations in Mn0.07Mg0.93Cr2O4 by single-crystalline neutron scattering. The correlation lengths are evaluated to be 12.7 angstrom and 4.4 angstrom along parallel and perpendicular to the propagation vector, respectively. The spiral rotational plane is estimated to be the proper-screw type rather than the cycloid-screw one. This fact suggests that Mn moments stabilize the cycloidal structure, generating the ferroelectricity in the parent material MnCr2O4., IOP PUBLISHING LTD
INTERNATIONAL CONFERENCE ON FRUSTRATION IN CONDENSED MATTER (ICFCM), 2011, [Reviewed]

Spin-orbit coupling inactivity of Co2+ ion in geometrically frustrated magnet GeCo2O4
Keisuke Tomiyasu; Ayaka Tominaga; Shigeo Hara; Hirohiko Sato; Tadataka Watanabe; Shin-Ichi Ikeda; Haruhiro Hiraka; Kazuaki Iwasa; Kazuyoshi Yamada, We report single-crystal neutron diffraction studies on a spinel antiferromagnet GeCo2O4, which exhibits magnetic order with a trigonal propagation vector and tetragonal lattice expansion (c/a similar or equal to 1.001) below T-N = 21 K. For this inconsistency between spin and lattice in symmetry, magnetic Bragg reflections with a tetragonal propagation vector were discovered below TN. We discuss spin and orbital states of Co2+ ion underlying the new magnetic component., IOP PUBLISHING LTD
INTERNATIONAL CONFERENCE ON FRUSTRATION IN CONDENSED MATTER (ICFCM), 2011, [Reviewed]

New Aspects of Electronic Ordered States due to f (2) Configuration of Pr-Based Systems
Kazuaki Iwasa; Kotaro Saito; Lijie Hao, Strong hybridization between conduction electrons and f(2) electrons in a trivalent Pr ion is a recent attractive subject. For example, the Pr-filled skutterudite compounds have been extensively studied. Pr(Ru1-xRhx)(4)P-12 exhibits the reentrant-like behavior of the metal-nonmetal transition, and PrFe4P12 the heavy-fermion state followed by the nonmetallic ordering. In this article, we review briefly these phenomena characterized by the staggered structures of the totally symmetric order parameters of f(2) state. We also demonstrate the higher-order magnetic scattering of polarized neutron to investigate quantum state levels in the f electron systems, which is expected to be carried out at the pulsed neutron facility J-PARC MLF., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Jan. 2011

Antiferromagnetic Alignment of Magnetic Dipolar Moments Observed by Neutron Powder Diffraction in Rare-Earth Palladium Bronze PrPd3S4
Eiichi Matsuoka; Daichi Usui; Yuta Sasaki; Masanori Watahiki; Kazuaki Iwasa; Hiroshi Shida; Kenji Ohoyama; Hideya Onodera, Neutron powder diffraction and inelastic-neutron-scattering experiments have been performed on PrPd3S4 as well as magnetization and magnetic-susceptibility measurements of single-crystalline samples to examine the order parameter below T-M = 1.56 K. From the results of the inelastic-neutron-scattering and magnetization measurements, the ground state of the J-multiplet of Pr3+ under a cubic crystalline electric field with T-h symmetry was determined to be the Gamma 4((2)) triplet with the first excited state situated above 390 K. Since the dipolar operator and the T-alpha- and T-beta -type octupolar operators are proportional to the same matrix with the bases of the ground Gamma 4((2)) triplet, the antiferromagnetic (AFM) alignment of the magnetic dipolar moments below TM observed in the neutron powder diffraction experiment implies two possible ordering states, i.e., AFM ordering induced by a dipolar interaction and antiferro-octupolar ordering induced by an octupolar interaction., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Jun. 2010

Crystal field excitations in PrFe4Sb12 synthesized under high pressure
K. Kuwahara; K. Tanaka; T. Saito; S. Tatsuoka; K. Iwasa; M. Watanabe; Y. Aoki; H. Sato; M. Kohgi; K. Iwasa; H. Sugawara; C. Stock; D. T. Adroja
J. Phys.: Conf. Ser., Mar. 2010, [Reviewed]

Pressure-Induced Antiferromagnetic Order in Filled Skutterudite PrFe4P12 Studied by Single-Crystal High-Pressure Neutron Diffraction
Toyotaka Osakabe; Keitaro Kuwahara; Daichi Kawana; Kazuaki Iwasa; Daisuke Kikuchi; Yuji Aoki; Masahumi Kohgi; Hideyuki Sato, The order parameter in the pressure-induced insulating phase of the filled skutterudite compound PrFe4P12 has been investigated using a high-pressure single-crystal neutron diffraction technique. Clear evidence of the antiferromagnetic order with the propagation vector q = (1, 0, 0) was observed in the insulating phase above 2.7 GPa. The q = (1, 0, 0) structure is identical with that in the nonmagnetic ordered phase below 2.5 GPa and with the nesting property of the Fermi surface. The observed magnetic moment of the Pr ion is 2 mu(B) and almost pressure-independent up to at least 4.2 GPa. The 2 mu(B) magnetic moment originates from the dipole in the low-lying quasi-quartet crystal field state. The pressure-induced antiferromagnetic structure at 3.2 GPa is suppressed by applying a magnetic field of about 1.5 T, which is interpreted as a flop of magnetic moments into the alignment of the ferromagnetic state. This brings about a steep decrease in the electrical resistivity due to the disappearance of the antiferromagnetic superstructure., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Mar. 2010

Temperature evolution of crystal field splitting in Pr-filled skutterudite
K. Iwasa; K. Saito; Y. Murakami; H. Sugawara, Crystal field states of Pr 4f electrons of PrOs4P12 and PrRu4Sb12 were investigated by inelastic neutron scattering. Different spectral widths between two excitations from the ground state singlet to the triplets and their temperature evolutions are well reproduced by the theory based on the exchange coupling between 4f and conduction electrons (Becker K W et al. 1977 Z. Physik B 28 9). Shift of level energies by around 1 meV below 60 K were also observed. The results support the p-f hybridization effect in Pr-filled skutterudites. © 2010 IOP Publishing Ltd., Institute of Physics Publishing
Journal of Physics: Conference Series, 2010

Current understanding of the heavy fermion superconductivity in PrOs ₄Sb₁₂
Sato, H.; Tanaka, K.; Kikuchi, D.; Namiki, T.; Higashinaka, R.; Aoki, Y.; Kohgi, M.; Sugawara, H.; Kuwahara, K.; Iwasa, K.
Physica C: Superconductivity and its Applications, 2010, [Reviewed]

Electric-dipole-active magnetic resonance in the conical-spin magnet Ba2Mg2Fe12O22
Kida N; Okuyama D; Ishiwata S; Taguchi Y; Shimano R; Iwasa K; Arima T; Tokura Y, Electric-field (E) drive of magnetic resonance in a solid has been a big challenge in condensed-matter physics and emerging spintronics. We demonstrate the appearance of distinct magnetic excitations driven by the light E component in a hexaferrite Ba2Mg2Fe12O22. In the conical-spin state even with no spontaneous electric polarization (P-s), a sharp and intense resonance is observed around 2.8 meV for the light E vector parallel to the magnetic propagation vector in accord with the inelastic neutron scattering spectrum at the magnetic zone center. As the generic characteristic of the conical state, a weak magnetic field (similar to 2 kOe) can modify the spin structure, leading to a remarkable change (terahertz magnetochromism) in spectral shape and intensity (by similar to 200%) of the electric-dipole-active magnetic resonance. The present observation implies that potentially many magnets with noncollinearly ordered spins may host such an electric-dipole-active resonance, irrespective of the presence or absence of P-s., AMER PHYSICAL SOC
PHYSICAL REVIEW B, Dec. 2009, [Reviewed]

Magnetic octupole order in Ce_0.7 La_0.3 B₆: A polarized neutron diffraction study
Kuwahara, K.; Iwasa, K.; Kohgi, M.; Aso, N.; Sera, M.; Iga, F.; Matsuura, M.; Hirota, K., Recently, in phase IV of CexLa1-xB6, weak but distinct superlattice reflections from the order parameter of phase IV have been detected by our unpolarized neutron scattering experiment [K. Kuwahara, K. Iwasa, M. Kohgi, N. Aso, M. Sera, F. Iga, J. Phys. Soc. Japan 76 (2007) 093702]. The scattering vector dependence of the intensity of superlattice reflections is quite unusual; the intensity is stronger for high scattering vectors. This result strongly indicates that the order parameter of phase IV is the magnetic octupole. However, the possibility that the observed superlattice reflections are due to lattice distortions could not be completely ruled out only on the basis of the unpolarized neutron scattering experiment. To confirm that the superlattice reflections are magnetic, therefore, we have performed a single crystal polarized neutron diffraction experiment on Ce0.7La0.7B6. The obtained result has clearly shown that the time reversal symmetry is broken by the order parameter of phase IV. This is further evidence for the magnetic octupole order in CexLa1-xB6.
Physica B: Condensed Matter, Sep. 2009, [Reviewed]

Electronic hybridization effect on 4f electron crystal field states of PrOs4P12
Kazuaki Iwasa; Kotaro Saito; Youichi Murakami; Hitoshi Sugawara, Crystal-field excitation spectra of Pr 4f electron state in the filled skutterudite PrOs4P12 measured by inelastic neutron scattering experiment evolve distinctly with temperature variation. The spectral widths of excitations from the ground-state singlet to the two triplets and their temperature dependences are well reproduced by the theory based on the exchange coupling between 4f and conduction electrons. The shift of level energies by around 1 meV below 60 K indicates modification of crystal-field potential with variation of thermal population of 4f electron crystal-field states. The spectral evolution is consistent with the specific heat data that deviates from the calculated one for the well-localized 4f electron. The result supports the effect of p-f hybridization between Pr 4f and P p states in PrOs4P12., AMER PHYSICAL SOC
PHYSICAL REVIEW B, Jun. 2009

Excitation spectrum of PrOs₄Sb₁₂ under a magnetic field
Raymond, S.; Kuwahara, K.; Kaneko, K.; Iwasa, K.; Kohgi, M.; Hiess, A.; Flouquet, J.; Metoki, N.; Sugawara, H.; Aoki, Y.; Sato, H.
Journal of Physics Condensed Matter, 2009, [Reviewed]

Magnetic Excitations in Heavy Electron State of Filled Skutterudite Pr_xLa_<1-x>Fe_4P_<12> (x=1.00 and 0.85)(Condensed matter: electronic structure and electrical, magnetic, and optical properties)
Iwasa Kazuaki; Hao Lijie; Hasegawa Tomoo; HORIUCHI Kenji; MURAKAMI Youichi; OTSUKI Junya; KURAMOTO Yoshio; KOHGI Masahumi; KUWAHARA Keitaro; SUGAWARA Hitoshi; AOKI Yuji; SATO Hideyuki, Lead, PrFe_4P_<12> exhibits clear heavy electron behaviors as well as the phase transition to an antiferro-type ordering of 4f electron state. In this paper, we report on inelastic neutron scattering results for powdered samples of Pr_xLa_<1-x>Fe_4P_<12> (x=1.00 and 0.85). A clear quasielastic magnetic response is observed, and no distinct signal is seen for crystal-field (CF) excitations in the heavy electron state. A model with strong hybridization between conduction electrons and Pr^<3+> 4f^2 electrons [J. Otsuki et al.: J. Phys. Soc. Jpn. 74 (2005) 200 and 2082] is consistent with the observed magnetic response. This result shows that the heavy electron behavior of Pr_xLa_<1-x>Fe_4P_<12> (x=1.00 and 0.85) originates from the Kondo effect associated with low-lying singlet-triplet CF states., 一般社団法人日本物理学会
Journal of the Physical Society of Japan, Jun. 2008, [Reviewed]

Magnetic excitations in heavy electron state of filled skutterudite PrxLa1-xFe4P12 (x=1.00 and 0.85)
Kazuaki Iwasa; Lijie Hao; Tomoo Hasegawa; Kenji Horiuchi; Youichi Murakami; Junya Otsuki; Yoshio Kuramoto; Masahumi Kohgi; Keitaro Kuwahara; Hitoshi Sugawara; Yuji Aoki; Hideyuki Sato, PrFe4P12 exhibits clear heavy electron behaviors as well as the phase transition to an antiferro-type ordering of 4f electron state. In this paper, we report on inelastic neutron scattering results for powdered samples of PrxLa1-xFe4P12 (x = 1.00 and 0.85). A clear quasielastic magnetic response is observed, and no distinct signal is seen for crystal-field (CF) excitations in the heavy electron state. A model with strong hybridization between conduction electrons and Pr3+ 4f(2) electrons [J. Otsuki et al.: J. Phys. Soc. Jpn. 74 (2005) 200 and 2082] is consistent with the observed magnetic response. This result shows that the heavy electron behavior of PrxLa1-xFe4P12 (x = 1.00 and 0.85) originates from the Kondo effect associated with low-lying singlet-triplet CF states., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Jun. 2008, [Reviewed]

Spin-Singlet Ground State in the Two-Dimensional Frustrated Triangular Lattice : YbAl_3C_3(Condensed matter : electronics structure and electrical, magnetic, and optical properties)
Kato Yoshiaki; Kosaka Masashi; Nowatari Hiromi; SAIGA Yuta; YAMADA Atsushi; KOBIYAMA Takuya; KATANO Susumu; OHOYAMA Kenji; SUZUKI Hiroyuki S.; ASO Naofumi; IWASA Kazuaki, We present the highly frustrated phenomena observed in YbAl3C3 with a spin gap. The inelastic neutron spectra of low-lying magnetic excitations at low temperatures are quite similar to those of SrCU2(BO3)(2) and (CuCl)LaNb2O7 that exhibit a dimer ground state in a two-dimensional quantum spin system. The structure of the first excited triplet state is directly clarified by inelastic neutron scattering experiments with a higher energy resolution. Furthermore, it becomes clear that the characteristic magnetic excitations remain within a high-temperature region. The result of the specific heat measurement also shows an anomaly associated with the formation of dimerized Yb ions. We conclude that a long-range magnetic order is suppressed by a large geometrical spin frustration, resulting in the stabilization of the dimer ground state., 一般社団法人日本物理学会
Journal of the Physical Society of Japan, May 2008, [Reviewed]

Spin-singlet ground state in the two-dimensional frustrated triangular lattice: YbAl3C3
Yoshiaki Kato; Masashi Kosaka; Hiromi Nowatari; Yuta Saiga; Atsushi Yamada; Takuya Kobiyama; Susumu Katano; Kenji Ohoyama; Hiroyuki S. Suzuki; Naofumi Aso; Kazuaki Iwasa, We present the highly frustrated phenomena observed in YbAl3C3 with a spin gap. The inelastic neutron spectra of low-lying magnetic excitations at low temperatures are quite similar to those of SrCU2(BO3)(2) and (CuCl)LaNb2O7 that exhibit a dimer ground state in a two-dimensional quantum spin system. The structure of the first excited triplet state is directly clarified by inelastic neutron scattering experiments with a higher energy resolution. Furthermore, it becomes clear that the characteristic magnetic excitations remain within a high-temperature region. The result of the specific heat measurement also shows an anomaly associated with the formation of dimerized Yb ions. We conclude that a long-range magnetic order is suppressed by a large geometrical spin frustration, resulting in the stabilization of the dimer ground state., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, May 2008, [Reviewed]

Competition of Magnetic and Quadrupolar Order Parameters in HoB_4(Condensed matter: electronic structure and electrical, magnetic, and optical properties)
Okuyama Daisuke; Matsumura Takeshi; Mouri Takuya; ISHIKAWA Naoko; OHOYAMA Kenji; HIRAKA Haruhiro; NAKAO Hironori; IWASA Kazuaki; MURAKAMI Youichi, The successive magnetic phase transitions of HoB4 with $T_{\text{N1 } }=7.1$ K and $T_{\text{N2 } }=5.7$ K have been investigated in detail by neutron and X-ray diffraction. Since Ho ions in the $c$-plane form a Shastry–Sutherland lattice, geometrical frustration has been expected in this compound. Below $T_{\text{N1 } }$, HoB4 exhibits an incommensurate antiferromagnetic order with $\mathbf{q}=(\delta, \delta, \delta')$ ($\delta=0.022$, $\delta'=0.43$), followed by a first-order transition at $T_{\text{N2 } }$ into a commensurate order with $\mathbf{q}=(0, 0, 0)$, where four magnetic moments are antiferromagnetically coupled in a unit cell. After determining the magnetic structures of the two phases by neutron powder diffraction, we pay particular attention to diffuse scatterings responsible for the critical behavior. Very broad diffuse scatterings, extending almost to the zone boundary, are observed already in the paramagnetic phase at around $\mathbf{q}=(0, 0, 0)$ and $(0, 0, 1/2)$ with magnetic correlation lengths of $\xi < 10$ Å. Below $T_{\text{N1 } }$, a strong diffuse scattering develops in a more concentrated region at around $\mathbf{q}=(0, 0, \delta')$ with $\xi\sim 30$ Å, followed by the appearance of a Bragg peak at $(\delta, \delta, \delta')$. Simultaneously, a sharp Bragg peak corresponding to $\mathbf{q}=(0, 0, 0)$ also develops at $(1, 0, 1)$ upon diffuse scattering. This complex critical behavior is discussed from the viewpoint of competing order parameters of magnetic and quadrupolar origins. The striking resemblance of the critical behavior to that of HoB2C2 with a square lattice of Ho is interpreted as a manifestation of a universality for a three-dimensional system with competing magnetic and quadrupolar order parameters and a long-ranged RKKY interaction. It is considered that the microscopic difference in interionic interaction due to the difference in crystal structure becomes less prominent in the critical behavior as the correlation length becomes much larger than the lattice constant. On the other hand, the strong diffuse scattering in HoB4, which is hardly detected in HoB2C2, might be ascribed to geometrical frustration. The softening of the elastic constant in HoB4 and HoB2C2 is also discussed., 一般社団法人日本物理学会
Journal of the Physical Society of Japan, Apr. 2008, [Reviewed]

Inelastic neutron scattering from PrFe4 P12 at low temperatures and under high magnetic fields
Park, J.-G.; Adroja, D.T.; McEwen, K.A.; Kohgi, M.; Iwasa, K.
Physical Review B - Condensed Matter and Materials Physics, 2008

Magnetic Correlation in the Ordered Phase of CeOs4Sb12
Kazuaki Iwasa; Shouhei Itobe; Changping Yang; Youichi Murakami; Masahumi Kohgi; Keitaro Kuwahara; Hitoshi Sugawara; Hideyuki Sato; Naofumi Aso; Takashi Tayama; Toshiro Sakakibara, We performed neutron diffraction and magnetization measurements to reveal the nature of phase transition of a Kondo semiconductor CeOs4Sb12. Weak antiferromagnetic (AFM) reflections characterized by a wave vector q = (1 0 0) were observed, and the ordered moment value is around 0.07 mu(B)/Ce at zero magnetic field. The AFM structure is rapidly suppressed by magnetic field of 1 T, in contrast to the transition temperature suggested to be enhanced by magnetic field. Only ferromagnetic correlation is observed above 1 T. Such drastic variation of the magnetic correlation is closely connected into the transport properties; the AFM ordered phase below 1 T and the induced ferromagnetic state above 1 T correspond to the semiconducting and metallic states, respectively., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Jan. 2008, [Reviewed]

Inelastic neutron scattering study of the heavy fermion superconductor PrOs4Sb12
Raymond S; Kuwahara K; Kaneko K; Iwasa K; Kohgi M; Hiess A; Measson M. -A; Flouquet J; Metoki N; Sugawara H; Aoki Y; Sato H, The Physical Society of Japan
Journal of the Physical Society of Japan, 2008, [Reviewed]

Crystal field excitations in the filled skutterudite NdOs₄ Sb₁₂
Kuwahara, K.; Takagi, M.; Iwasa, K.; Itobe, S.; Kikuchi, D.; Aoki, Y.; Kohgi, M.; Sato, H.; Sugawara, H.
Physica B: Condensed Matter, 2008, [Reviewed]

Novel Features Realized in the Filled Skutterudite Structure
Sato Hideyuki; Kikuchi Daisuke; Tanaka Kenya; Ueda Makoto; Aoki Hidekazu; Ikeno Tsuyoshi; Tatsuoka Sho; Kuwahara Keitaro; Aoki Yuji; Kohgi Masafumi; Sugawara Hitoshi; Iwasa Kazuaki; Harima Hisatomo, The Physical Society of Japan
Journal of the Physical Society of Japan, 2008, [Reviewed]

Field induced magnetic moment distribution in the ordered phase of PrFe4P12
Iwasa Kazuaki; Hao Lijie; Murakami Youichi; Kohgi Masahumi; Kuwahara Keitaro; Sugawara Hitoshi; Matsuda Tatsuma D; Aoki Yuji; Sato Hideyuki; Mignot Jean-Michel; Gukasov Arsen, The Physical Society of Japan
Journal of the Physical Society of Japan, 2008, [Reviewed]

Detection of Neutron Scattering from Phase IV of Ce_<0.7>La_<0.3>B_6 : A Confirmation of the Octupole Order(Condensed matter: electronic structure and electrical, magnetic, and optical properties)
Kuwahara Keitaro; Iwasa Kazuaki; Kohgi Masahumi; ASO Naofumi; SERA Masafumi; IGA Fumitoshi, We have performed a single crystal neutron scattering experiment on Ce_La_<0.3>B_6 to microscopically investigate the order parameter of phase IV. Below the phase transition temperature 1.5K of phase IV, weak but distinct superlattice reflections at the scattering vector K=(h/2, h/2, l/2) (h, l=odd number) have been observed for the first time by neutron scattering. The intensity of the superlattice reflections is stronger for high scattering vectors, which is quite different from the usual magnetic form factor of magnetic dipoles. This result directly evidences that the order parameter of phase IV has a complex magnetization density, consistent with the recent experimental and theoretical prediction in which the order parameter is the magnetic octupoles T^β with Γ_5 symmetry of the point group O_h. Neutron scattering experiments using short wavelength neutrons, as done in this study, could become a general method to study the high-rank multipoles in f electron systems., 一般社団法人日本物理学会
Journal of the Physical Society of Japan, Sep. 2007, [Reviewed]

Detection of neutron scattering from phase IV of Ce0.7La0.3B6: A confirmation of the octupole order
Keitaro Kuwahara; Kazuaki Iwasa; Masahumi Kohgi; Naofumi Aso; Masafumi Sera; Fumitoshi Iga, We have performed a single crystal neutron scattering experiment on Ce0.7La0.3B6 to microscopically investigate the order parameter of phase IV. Below the phase transition temperature 1.5 K of phase IV, weak but distinct superlattice reflections at the scattering vector K = (h/2, h/2, l/2) (h, l = odd number) have been observed for the first time by neutron scattering. The intensity of the superlattice reflections is stronger for high scattering vectors, which is quite different from the usual magnetic form factor of magnetic dipoles. This result directly evidences that the order parameter of phase IV has a complex magnetization density, consistent with the recent experimental and theoretical prediction in which the order parameter is the magnetic octupoles T-beta with Gamma(5) symmetry of the point group Oh. Neutron scattering experiments using short wavelength neutrons, as done in this study, could become a general method to study the high-rank multipoles in f electron systems., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Sep. 2007, [Reviewed]

The unconventional superconductivity of skutterudite PrOS4Sb12: Time-reversal symmetry breaking and adjacent field-induced quadrupole ordering
Yuji Aoki; Takashi Tayama; Toshiro Sakakibara; Keitaro Kuwahara; Kazuaki Iwasa; Masahumi Kohgi; Wataru Higemoto; Douglas E. MacLaughlin; Hitoshi Sugawara; Hideyuki Sato, This review presents a summary and evaluation of the experimental properties of unconventional superconductivity in PrOs4Sb12. After a brief introduction of filled skutterudites, we argue that the normal-state properties of PrOs4Sb12 are quite different from ordinary heavy-fermion superconductors, in the sense that the 4f-electrons seem to be well localized even at low temperatures where the superconductivity appears. This is reflected in the existence of a field-induced antiferro-quadrupole ordering of Pr 4f-electrons. It is shown that the 4f collective excitations can be described as quadrupolar excitons. Their strong temperature dependence in close correlation with the superconductivity suggests a conjecture that the superconducting mechanism may involve quadrupolar-exciton-mediated pairing of some kind. Although the structure of the superconducting order parameter is far from conclusive, outstanding experimental observations reported to date reveal the uniqueness of the unconventional superconducting state. Special focus is given to time-reversal symmetry breaking in the superconducting state. The article concludes with a discussion of some key issues and desirable future work., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, May 2007

Antiferromagnetic ordering in the filled skutterudite semiconductor CeOs4Sb12
K. Iwasa; C. P. Yang; M. Kohgi; H. Sugawara; H. Sato; N. Aso, Neutron diffraction experiment was performed to investigate a nature of the ordered phase below 0.9K of the filled skutterudite Kondo semiconductor CeOs4Sb12. We observed antiferromagnetic ordering with a tiny magnetic moment of around 0: 03 mu(B)/f.u. characterized by the wave vector q = (100). The magnetic ordered state can be interpreted as a spin density wave formation due to the nesting of the small Fermi surface within the hybridization gap. (c) 2006 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, Mar. 2007

Fractal dimension in percolating Heisenberg antiferromagnets
S. Itoh; R. Kajimoto; M.A. Adams; M.J. Bull; K. Iwasa; N. Aso; H. Yoshizawa; T. Takeuchi, Elsevier BV
Journal of Magnetism and Magnetic Materials, Mar. 2007

Inelastic neutron scattering measurements in a quadrupolar ordering compound YbSb
Oyamada, A.; Kuwahara, K.; Ohoyama, K.; Iwasa, K.; Kohgi, M.; Maegawa, S.
Journal of Magnetism and Magnetic Materials, Mar. 2007, [Reviewed]

Phonon dispersion curves in CeOs₄Sb₁₂
Yang, C.P.; Wang, H.; Iwasa, K.; Kohgi, M.; Sugawara, H.; Sato, H.
Journal of Physics Condensed Matter, 2007

Antiferromagnetic ordering of CeOs₄Sb₁₂ below 1 K
Yang, C.P.; Wang, H.; Hu, J.F.; Iwasa, K.; Kohgi, M.; Sugawara, H.; Sato, H.
Journal of Physical Chemistry C, 2007

Lattice dynamics of the filled skutterudite CeOs₄Sb₁₂
Yang, C.P.; Wang, H.; Iwasa, K.; Kohgi, M.; Sugawara, H.; Sato, H.
Applied Physics Letters, 2007

Magnetic phase transition in HoB₄ studied by neutron diffraction
Okuyama, D.; Matsumura, T.; Iwasa, K.; Murakami, Y.
Journal of Magnetism and Magnetic Materials, 2007, [Reviewed]

Novel electronic states realized in the filled skutterudites containing rare earth elements with more than one 4f-electrons
Sato, H.; Kikuchi, D.; Tanaka, K.; Aoki, H.; Kuwahara, K.; Aoki, Y.; Kohgi, M.; Sugawara, H.; Iwasa, K.
Journal of Magnetism and Magnetic Materials, 2007, [Reviewed]

Structural Transformation on the Pressure-Induced Metal-Insulator Transition in PrFe_4P_<12>(Condensed matter: structure and mechanical and thermal properties)
Kawana Daichi; Kuwahara Keitaro; Sato Masashi; TAKAGI Masatoshi; AOKI Yuji; KOHGI Masahumi; SATO Hideyuki; SAGAYAMA Hajime; OSAKABE Toyotaka; IWASA Kazuaki; SUGAWARA Hitoshi, We report the first X-ray diffraction experiments of PrFe_4P_<12> under high pressure. We discovered a symmetry lowering from cubic to orthorhombic or lower at the metal-insulator transition temperature, accompanied by a jump in the lattice constant, which indicates a first-order phase transition. The superlattice reflections at q=(1, 0, 0) observed in the low-pressure nonmagnetic ordered phase are found to disappear in the insulating phase. The temperature dependence of the lattice constant and the absence of the superlattice reflections are well explained by taking into account an antiferromagnetic ordering., 一般社団法人日本物理学会
Journal of the Physical Society of Japan, Nov. 2006, [Reviewed]

Fractal structure and critical scattering in the three-dimensional percolating antiferromagnet,
S. Itoh; R. Kajimoto; K. Iwasa; N. Aso; M.J. Bull; M.A. Adams; T. Takeuchi; H. Yoshizawa, Elsevier BV
Physica B: Condensed Matter, Nov. 2006

Strongly correlated phenomena in Pr-based filled skutterudite compounds detected by neutron scattering
Masahumi Kohgi; Kazuaki Iwasa; Keitaro Kuwahara, Recent neutron scattering studies on the Pr-based filled skutterudite compounds, which show strongly correlated phenomena, are reviewed. It was found that the 4f electron states of PrFe4P12 and PrRu4P12 are strongly hybridized with conduction electrons. It is consistent with the heavy-fermion properties observed for PrFe4P12. These states turn out to be the quadrupole ordering state (PrFe4P12) or the charge density wave state (PrRu4P12) at low temperatures. The lowest crystal field excited state of PrOs4Sb12 was found to show an excitonic behavior, which is ascribed to the quadrupolar interaction between Pr atoms. The strong temperature dependence of the excitonic excitations through the superconducting phase transition indicates a close correlation of the excitons with the superconductivity of PrOs4Sb12. The importance of the characteristic Fermi surface topology and the effects of the p-f hybridization is discussed to understand the variety of the strongly correlated phenomena in these compounds based on the experimental results. (c) 2006 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
PHYSICA B-CONDENSED MATTER, Nov. 2006, [Reviewed]

Structural transformation on the pressure-induced metal-insulator transition in PrFe4P12
Daichi Kawana; Keitaro Kuwahara; Masashi Sato; Masatoshi Takagi; Yuji Aoki; Masahumi Kohgi; Hideyuki Sato; Hajime Sagayama; Toyotaka Osakabe; Kazuaki Iwasa; Hitoshi Sugawara, We report the first X-ray diffraction experiments of PrFe4P12 under high pressure. We discovered a symmetry lowering from cubic to orthorhombic or lower at the metal-insulator transition temperature, accompanied by a jump in the lattice constant, which indicates a first-order phase transition. The superlattice reflections at q = (1, 0, 0) observed in the low-pressure nonmagnetic ordered phase are found to disappear in the insulating phase. The temperature dependence of the lattice constant and the absence of the superlattice reflections are well explained by taking into account an antiferromagnetic ordering., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Nov. 2006

Structural transformation on the pressure-induced metal-insulator transition in PrFe4P12
Daichi Kawana; Keitaro Kuwahara; Masashi Sato; Masatoshi Takagi; Yuji Aoki; Masahumi Kohgi; Hideyuki Sato; Hajime Sagayama; Toyotaka Osakabe; Kazuaki Iwasa; Hitoshi Sugawara, We report the first X-ray diffraction experiments of PrFe4P12 under high pressure. We discovered a symmetry lowering from cubic to orthorhombic or lower at the metal-insulator transition temperature, accompanied by a jump in the lattice constant, which indicates a first-order phase transition. The superlattice reflections at q = (1, 0, 0) observed in the low-pressure nonmagnetic ordered phase are found to disappear in the insulating phase. The temperature dependence of the lattice constant and the absence of the superlattice reflections are well explained by taking into account an antiferromagnetic ordering., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Nov. 2006

Magnetic form factor of URu2Si2
K. Kuwahara; M. Kohgi; K. Iwasa; M. Nishi; K. Nakajima; M. Yokoyama; H. Amitsuka, We report the field-induced magnetic form factor of the heavy-electron system URu2Si2 obtained by using polarized neutrons. The neutron experiments were performed on the two single crystals at 60 K by applying a magnetic field of 6 T along the tetragonal c-axis. The observed magnetic form factor is close to the theoretical 5f form factor of the free U3 + or U4 + ions calculated by the dipole approximation as other U-based intermetallic superconductors. However, the extrapolated value at sin ・ﾆ / ・ﾉ = 0 ( 0.07 ・ﾊB / U ) is smaller than the bulk magnetization value ( 0.10 ・ﾊB / U ). Therefore, this result indicates some contribution other than 5f electrons to the bulk magnetization of URu2Si2. ? 2006 Elsevier B.V. All rights reserved., ELSEVIER
Physica B: Condensed Matter, May 2006, [Reviewed]

Large softening of acoustic phonons in PrOs₄ Sb₁₂
Iwasa, K.; Kohgi, M.; Sugawara, H.; Sato, H.
Physica B: Condensed Matter, 2006

Kondo interactions in the CeOs₄Sb₁₂ skutterudite studied by inelastic neutron scattering
Yang, C.-P.; Zhou, Z.-H.; Wang, H.; Iwasa, K.; Kohgi, M.
Wuli Xuebao/Acta Physica Sinica, 2006

Evidence of spin density wave of CeOs₄Sb₁₂
Yang, C.; Zhou, Z.; Wang, H.; Hu, J.; Iwasa, K.; Sugawara, H.; Sato, H.
Rare Metals, 2006

Crystal field effects in CeOs₄Sb₁₂ as determined by inelastic neutron scattering
Yang, C.P.; Wang, H.; Iwasa, K.; Kohgi, M.; Sugawara, H.; Sato, H.
Applied Physics Letters, 2006

High-pressure X-ray diffraction study of PrFe₄P₁₂
Kawana, D.; Sagayama, H.; Sato, M.; Kuwahara, K.; Aoki, Y.; Kohgi, M.; Sato, H.; Iwasa, K.; Sugawara, H.
Physica B: Condensed Matter, 2006, [Reviewed]

p-f hybridization effect on the metal-nonmetal phase transition in PrRu₄ P₁₂
Hao, L.; Iwasa, K.; Hasegawa, T.; Takagi, T.; Horiuchi, K.; Mori, Y.; Murakami, Y.; Kuwahara, K.; Kohgi, M.; Sugawara, H.; Saha, S.R.; Aoki, Y.; Sato, H.
Physica B: Condensed Matter, 2006, [Reviewed]

Inelastic neutron scattering study on low-energy excitations of the heavy-fermion superconductor PrOs₄Sb₁₂
Kuwahara, K.; Iwasa, K.; Kohgi, M.; Kaneko, K.; Metoki, N.; Raymond, S.; M{\'e}asson, M.-A.; Flouquet, J.; Sugawara, H.; Aoki, Y.; Sato, H.
Physica B: Condensed Matter, 2006, [Reviewed]

Inelastic neutron scattering from CeOs(4)Sb12
CP Yang; M Kohgi; K Iwasa; H Sugawara; H Sato, PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Oct. 2005

Role of p-f hybridization in the metal-nonmetal transition of PrRu4P12
K Iwasa; LJ Hao; T Hasegawa; T Takagi; K Horiuchi; Y Mori; Y Murakami; K Kuwahara; M Kohgi; H Sugawara; Saha, SR; Y Aoki; H Sato, Electronic state evolution in the metal-nonmetal transition of PrRu4P12 has been studied by X-ray and polarized neutron diffraction experiments. It has been revealed that, in the low-temperature nonmetallic phase, two inequivalent crystal-field (CF) schemes of Pr3+ 4f(2) electrons with Gamma(1) and Gamma((2))(4)-ground states are located at Pr1 and Pr2 sites forming the bee unit cell surrounded by the smaller and larger cubic Ruion sublattices, respectively. This modulated electronic state can be explained by the p-f hybridization mechanism taking two intermediate states of 4f(1) and 4f(3). The p-f hybridization effect plays an important role in the electronic energy gain in the metal-nonmetal transition originated from the Fermi surface nesting., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Jul. 2005

Electrical and magnetic properties of a single crystal UCu2Si2
TD Matsuda; Y Haga; S Ikeda; A Galatanu; E Yamamoto; H Shishido; M Yamada; J Yamaura; M Hedo; Y Uwatoko; T Matsumoto; T Tada; S Noguchi; T Sugimoto; K Kuwahara; K Iwasa; M Kohgi; R Settai; Y Onuki, We have succeeded in growing a high-quality single crystal of UCu2Si2 with the tetragonal structure by the Sn-flux method and measured the electrical resistivity, magnetic susceptibility, magnetization and specific heat. UCu2Si2 is found to order anti ferromagnetically below T-N = 106K, and follows a successive ferromagnetic ordering at T-C = 100 K. The magnetic properties are highly anisotropic, reflecting the crystal structure. An easy-axis of magnetization is found to be the [001] direction (c-axis) both in the antiferromagnetic and ferromagnetic phases, while the [100] direction (a-axis) corresponds to the hard-axis in magnetization. The magnetization curve in the antiferromagnetic phase indicates a clear metamagnetic transition at a low field of about 1 kOe and changes into a ferromagnetic magnetization curve below T-C = 100 K. The saturation moment is determined as 1.75 mu(B)/U at 2 K. The electronic specific heat coefficient is also determined as 20 mJ/(K(2.)mol)., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, May 2005

Spin density wave and charge density wave in the Kondo-lattice compound Ce(Ru_1-xRh_x)₂Si₂
Tabata, Y.; Taniguchi, T.; Kawarazaki, S.; Narumi, Y.; Kimura, S.; Tanaka, Y.; Katsumata, K.; Ishikawa, T.; Staub, U.; Kohgi, M.; Iwasa, K.
Physica B: Condensed Matter, 2005

Spin dynamics of quadrupole-ordered PrFe₄P₁₂
Park, J.-G.; Adroja, D.T.; McEwen, K.A.; Kohgi, M.; Iwasa, K.; Kwon, Y.S.
Physica B: Condensed Matter, 2005

Powder neutron diffraction studies of structure and magnetic Ce ordering in the strongly correlated electron compound Ce0.75La0.25B611
Fischer, P.; Iwasa, K.; Kuwahara, K.; Kohgi, M.; Hansen, T.; Kunii, S.
Physical Review B - Condensed Matter and Materials Physics, 2005

Quantum spin excitations in Yb₄As₃ under magnetic field
Kohgi, M.; Iwasa, K.; Mignot, J.-M.; Hiess, A.; Ochiai, A.; Aoki, H.
Physica B: Condensed Matter, 2005

Resonant and non-resonant x-ray scattering from GdB6
Kuwahara, K; Yamamoto, R; Kohgi, M; Nakao, H; Ishii, K; Iwasa, K; Murakami, Y; Kunii, S; Sagayama, H; Wakabayashi, Y; Sawa, H, We have performed resonant and non-resonant X-ray scattering on GdB6 to investigate the two successive phase transitions at TN=?15K and T*=?10K. Below TN, new superlattice reflection at the wave vector [141412], which is the same wave vector determined by the epithermal neutron diffraction, has been observed by X-ray scattering. In the temperature region between T* and TN, it was confirmed by the polarization analyses that the superlattice reflection is due to magnetic X-ray scattering. On the other hand, interestingly, the superlattice reflection below T* is mainly due to Thomson scattering. Unlike behavior expected from usual magnetoelastic effects, the wave vector of the lattice distortion is identical to that of the magnetic structure below T*. ? 2005 Elsevier B.V. All rights reserved.
Physica B-Condensed Matter, 2005, [Reviewed]

Evolution of 4f electron states in the metal-insulator transition of Pr Ru4 P12
Iwasa, K.; Hao, L.; Kuwahara, K.; Kohgi, M.; Saha, S.R.; Sugawara, H.; Aoki, Y.; Sato, H.; Tayama, T.; Sakakibara, T.
Physical Review B - Condensed Matter and Materials Physics, 2005, [Reviewed]

Magnetic excitations in the heavy-fermion superconductor PrOs ₄Sb₁₂
Raymond, S.; Flouquet, J.; Kuwahara, K.; Iwasa, K.; Kohgi, M.; Kaneko, K.; Metoki, N.; Sugawara, H.; Aoki, Y.; Sato, H.
Physica B: Condensed Matter, 2005, [Reviewed]

Direct observation of quadrupolar excitons in the heavy-fermion superconductor PrOs4Sb12
Kuwahara, K.; Iwasa, K.; Kohgi, M.; Kaneko, K.; Metoki, N.; Raymond, S.; M{\'e}asson, M.-A.; Flouquet, J.; Sugawara, H.; Aoki, Y.; Sato, H.
Physical Review Letters, 2005, [Reviewed]

Drastic evolution of 4f-electron states in the metal-insulator transition of PrRu₄P₁₂
Iwasa, K.; Hao, L.; Kuwahara, K.; Kohgi, M.; Saha, S.R.; Sugawara, H.; Aoki, Y.; Sato, H.
Physica B: Condensed Matter, 2005, [Reviewed]

Exotic properties of CeSb studied by x-ray diffraction
A Hannan; K Iwasa; M Kohgi; T Osakabe; H Kitazawa; T Suzuki, Various properties of the strongly correlated electron system CeSb at ambient pressure as well as under high pressures have been investigated employing X-ray as a probe. The satellite peaks caused by the lattice modulation of CeSb in its AFP3 phase at ambient pressure have been analyzed successfully. The satellite peak intensity pattern was explained based on a model considering different effective ionic sizes and the scattering form factors for Gamma(7) and Gamma(8)-like Ce3+ ions which appear in the ordered phase. The wave function for the Gamma(8)-like Ce ion with larger moment was found almost the same as that of J(z) = 5/2, which is consistent with the neutron diffraction experiment. At high pressures above about 1.9 GPa, rapid decrease of lattice constant was found below a certain critical temperature T-L, below which a sudden increase of electrical resistivity appears. This phenomenon can be explained by the formation of magnetic polaron state below this temperature., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Jul. 2004

Magnetic excitations in heavy-fermion superconductor PrOs4Sb12
K Kuwahara; K Iwasa; M Kohgi; K Kaneko; S Araki; N Metoki; H Sugawara; Y Aoki; H Sato, Magnetic excitations in a single crystal of heavy-fermion superconductor PrOs4Sb12 have been studied by inelastic neutron scattering (INS) at low temperatures under high magnetic fields. The crystal field (CF) excitations at 0.7 meV observed in a previous INS study of a polycrystal sample were confirmed in this study on a single crystal. The observed excitations in the zero magnetic field soften around a wave vector (1,0,0), which is the modulation vector of the field-induced antiferro-quadrupolar ordering, suggesting the presence of quadrupolar instability. The observed field dependence of excitations is better reproduced in a singlet ground-state model rather than in a non-Kramers doublet ground-state model. In a high resolution experiment, furthermore, the change of the excitation spectra at (1,0,0) was observed on passing through the superconducting transition temperature, indicating that the excitation and the superconductivity are closely related in PrOs4Sb12., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Jun. 2004

Crystal-lattice modulation of the metal-insulator transition system PrRu4P12 studied by X-ray diffraction
L. Hao; K. Iwasa; K. Kuwahara; M. Kohgi; S. R. Saha; H. Sugawara; Y. Aoki; H. Sato; C. Sekine; C. H. Lee; H. Harima, PrRu4P12 exhibits a metal-insulator phase transition at T-MI = 60 K: In the insulating phase below T-MI, X-ray superlattice reflections characterized by the wave vector q(0) = [1, 0, 0] were observed. The intensities at various reciprocal-lattice positions are reproduced by a model of modulated structure with the space group Pm(3) over bar in which Ru and P displacements are about 0.074% and 0.06%, respectively of the lattice constant. Thus, the transition can be interpreted as the gap formation due to the nesting of Fermi surface with 2k(F) = [1, 0; 0]. (C) 2004 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, May 2004, [Reviewed]

Neutron scattering study on the field-induced antiferro-quadrupolar ordering in the heavy fermion superconductor PrOs4Sb12
N. Metoki; K. Kaneko; S. Araki; M. Kohgi; K. Iwasa; K. Kuwahara; N. Bernhoeft; J. M. Mignot; A. Gukasov; H. Sato; Y. Aoki; H. Sugawara, We found the field-induced antiferro-quadrupole (AFQ) ordering in the Pr-based heavy fermion superconductor PrOs4Sb12 by means of neutron scattering. The field-induced staggered moment and the field dependence of the crystal field excitation spectra can be well understood in terms of the mean field Hamiltonian based on the singlet Gamma(1) with triplet Gamma(4) first excited state, where the quadrupolar interaction plays essential role for the AFQ ordering. (C) 2003 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, May 2004, [Reviewed]

Studies of unusual magnetic and electric properties of the low-carrier system CeP by synchrotron X-rays
M. Kohgi; K. Iwasa; K. Kuwahara; A. Hannan; D. Kawana; Y. Noda; T. Shobu; K. Katsumata; Y. Narumi; Y. Tabata, We have observed superlattice reflections from the low-carrier system CeP under high pressures up to 2 GPa and also under magnetic field up to 12.5 T by means of synchrotron X-ray diffraction. The observed intensities of superlattice reflections are well explained by a model that takes into account both the lattice and charge modulation due to the periodic arrangement of ferromagnetic double layers of Gamma(8)-like Cc ions in the lattice of Gamma(7) Cc ions. A new magnetic phase with the period of nine Cc planes was found in the experiment at the magnetic field of 12.5 T. (C) 2003 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
PHYSICA B-CONDENSED MATTER, Mar. 2004, [Reviewed]

Anomalous phonon excitations associated with strong p-f mixing effect of CeSb and CeBi
Iwasa, K.; Kohgi, M.; Braden, M.; Mignot, J.-M.; Kitazawa, H.; Suzuki, T.
Journal of Magnetism and Magnetic Materials, 2004

High pressure X-ray diffraction study of URu2Si2
K Kuwahara; H Sagayama; K Iwasa; M Kohgi; S Miyazaki; J Nozaki; J Nogami; M Yokoyama; H Amitsuka; H Nakao; Y Murakami, We have performed high pressure X-ray diffraction measurements on a powder sample of the tetragonal heavy-electron compound URu2Si2 at low temperatures and pressure up to 3 GPa, in order to investigate a pressure-induced phase transition at P-c = similar to1.5 GPa, which was indicated in the neutron diffraction experiment under pressure. The pressure variations of the lattice parameters a and c at 15 K decrease monotonously with increasing pressure. No discontinuity of the lattice parameters of URu2Si2 around P-c is observed within experimental error., JAGIELLONIAN UNIV PRESS
ACTA PHYSICA POLONICA B, Aug. 2003, [Reviewed]

Neutron-diffraction study of the unusual ordered phases of Ce0.75La0.25B6
K Iwasa; K Kuwahara; M Kohgi; P Fischer; A Donni; L Keller; TC Hansen; S Kunii; N Metoki; Y Koike; K Ohoyama, Ce0.75La0.25B6 shows paramagnetic phase (phase I), 4f-electron quadrupolar ordered phase (II), magnetically ordered phase (III), and an unknown phase IV. In order to investigate order parameters in phases III and IV, neutron diffraction experiments were performed down to 74 mK. Magnetic diffraction pattern measured in phase III is reproduced by a model in which spin arrangement is modified from the previously suggested structure for CeB6. No magnetic reflections were observed in phase IV. Thus, the order parameter in phase IV is expected to be 4f-electron multipoles rather than magnetic dipoles. (C) 2003 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV
PHYSICA B-CONDENSED MATTER, May 2003, [Reviewed]

Resonant X-ray scattering study on the filled skutterudite PrFe4P12
K Ishii; T Inami; Y Murakami; L Hao; K Iwasa; M Kohgi; Y Aoki; H Sugawara; H Sato; S Imada; H Nakao; H Sawa; Y Wakabayashi, Resonant X-ray scattering study was carried out to investigate an anomalous ordered state (T-A = 6.5 K) in the filled skutterudite PrFe4P12. At the Pr-L-III absorption edge, we observed resonant features in h + k + l = odd reflections, which are forbidden in the BCC structure above T-A. Because these reflections contain the difference of anomalous scattering factor between two Pr atoms in the BCC unit cell, and the ordered state is attributed to the ordering of two different electronic states of Pr. (C) 2002 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV
PHYSICA B-CONDENSED MATTER, May 2003, [Reviewed]

Evidence for magnetic-field-induced quadrupolar ordering in the heavy-fermion superconductor PrOs4Sb12
M Kohgi; K Iwasa; M Nakajima; N Metoki; S Araki; N Bernhoeft; JM Mignot; A Gukasov; H Sato; Y Aoki; H Sugawara, Neutron diffraction experiments on the heavy-fermion superconductor PrOs4Sb12 revealed that a small antiferromagnetic moment, parallel to [010] (y-direction), is induced in the field-induced phase (H parallel to z). The analysis, based on the Gamma(1) singlet ground state crystal field model, shows that antiferro-order of O-yz-type quadrupole moments of Pr ions is formed in the field-induced phase. This strongly suggests that the crystal field ground-state of Pr ions in PrOs4Sb12 is the Gamma(1) singlet and the quadrupolar ordering is induced due to level crossing with an excited state under a magnetic field., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, May 2003

Anisotropic thermoelectric properties of CeRhAs with superstructures
T Takabatake; T Suemitsu; T Sasakawa; J Kitagawa; K Umeo; M Nakajima; K Iwasa; M Kohgi, We report thermoelectric, magnetic and structural properties of the so-called Kondo semiconductor CeRhAs. The resistivity rho(T) along the three principal axes exhibits step-like anomalies at T-1 = 370, T-2 = 235 and T-3 = 165 K, respectively, and increases by two orders of magnitude on cooling to 1.5 K. Below T-1 an abrupt drop in the magnetic susceptibility along all the axes is associated with the cell doubling along the b- and c-axes, suggesting a charge-density-wave transition: Below T-3 the increase in the thermopower is strongest along the a-axis with a maximum of 186 muV/K at 35 K. The thermoelectric figure of merit becomes largest along the c-axis with the maximum value of 1.0 x 10(-3)/K, being comparable with that of CePd3., ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS
ACTA PHYSICA POLONICA B, Feb. 2003, [Reviewed]

Quadrupolar Ordering in Pr-filled Skutterudites Exhibiting Heavy-Electron State
Iwasa Kazuaki; Kohgi Masahumi, The Japanese Society for Neutron Science
hamon, 2003

Magnetic excitations in the heavy-electron and antiferro- quadrupolar-ordering system PrFe4P12
Iwasa K; Hao L; Nakajima M; Kohgi M; Sugawara H; Aoki Y; Sato H; Matsuda T. D
Acta Physica Polonica B, 2003, [Reviewed]

Antiferro-quadrupolar ordering of 4f-electron state in the filled skutterudite PrFe4P12
Hao L; Iwasa K; Nakajima M; Kawana D; Kuwahara K; Kohgi M; Sugawara H; Matsuda T. D; Aoki Y; Sato H
Acta Physica Polonica B, 2003, [Reviewed]

Anomalous critical scattering from a three-dimensional percolating antiferromagnet RbMn0.31Mg0.69F3
S Itoh; K Iwasa; MJ Bull, A neutron-diffraction experiment was performed to measure the critical scattering from a percolating antiferromagnet RbMn0.31Mg0.69F3, whose magnetic concentration is just at the percolation concentration for a cubic lattice, c(p) = 0.312. The magnetic scattering was observed at around the superlattice point (1/2, 1/2, 1/2). We found that the scattering function exhibits a non-Lorentzian line shape, S(q) = (q(2) + kappa(2))(-x) (q and kappa are the momentum transfer and the inverse correlation length, respectively), with the exponent x = 0.6+/-0.1 at the low temperature of 1.6 K, and that the exponent is attributed to the fractal structure of the percolating network. Also, the system was found to exhibit a crossover to the homogeneous state at high temperature., SPRINGER-VERLAG
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, Dec. 2002, [Reviewed]

High-pressure magnetic phase diagram of CeP studied by neutron diffraction
A Hannan; T Osakabe; M Kohgi; K Iwasa, Neutron-diffraction experiments have been performed in order to clarify the magnetic structures of CeP under pressures above 1.9GPa using a sapphire-anvil cell. The P-T phase diagram up to 2.8 GPa has been investigated. Some new phases have been found, for example the phase 2(+) (up arrow up arrow down arrow down arrow o o up arrow up arrow) under the pressure of 1.9 GPa. Type-IA anti-ferromagnetic structure (up arrow up arrow down arrow down arrow) was found below 22.5 and 45 K at 1.9 and 2.2 GPa, respectively. A phase characterized by the wave vector k = 1/3 and a ferromagnetic phase were observed in the pressure range 2.5-2.8 GPa., SPRINGER-VERLAG
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, Dec. 2002, [Reviewed]

Successive phase transitions and energy-gap formation in CeRhAs
T. Sasakawa; T. Suemitsu; T. Takabatake; Y. Bando; K. Umeo; M. H. Jung; M. Sera; T. Suzuki; T. Fujita; M. Nakajima; K. Iwasa; M. Kohgi; Ch. Paul; St. Berger; E. Bauer, Magnetic, transport, and x-ray diffraction measurements on single-crystal CeRhAs, the so-called Kondo insulator, have revealed successive transitions at T1 = 370, T2 = 235, and T3 = 165 K. Below T1, the unit cell is doubled along the b and c axes. Thereby, the resistivity jumps upwards and magnetic susceptibility in all the directions drops. Superlattice reflections at (0,1/3,1/3) and (1/3,0,0) appear at T<
T2. The latter suddenly increases below T3 where a transport gap is enhanced. These observations indicate that the gap formation is intimately related to lattice modulations., American Physical Society
Physical Review B - Condensed Matter and Materials Physics, Jul. 2002

Crystal-structure modulation in the anomalous low-temperature phase of PrFe₄P₁₂
Iwasa, K.; Watanabe, Y.; Kuwahara, K.; Kohgi, M.; Sugawara, H.; Matsuda, T.D.; Aoki, Y.; Sato, H., Nature of mysterious phase transition of the filled-skutterudite PrFe4P12 has been studied by X-ray diffraction experiments. Superlattice reflections characterized by a wave vector q = (1, 0, 0) were observed below the transition temperature of 6.5 K at zero magnetic field. The observed pattern in the reciprocal space is explained by the formation of modulated structure with dominant Fe-ion displacements by about 0.02% of the lattice constant. This result is consistent with the theoretically predicted nesting of Fermi surface producing a gap formation in electronic structure. © 2002 Elsevier Science B.V. All rights reserved.
Physica B: Condensed Matter, Mar. 2002

Staggered-field effect on the magnetic-field-induced magnetization of the one-dimensional antiferromagnet Yb₄As₃
Iwasa, K.; Kohgi, M.; Gukasov, A.; Mignot, J.-M.; Shibata, N.; Ochiai, A.; Aoki, H.; Suzuki, T.
Physical Review B - Condensed Matter and Materials Physics, 2002

Crystal-lattice modulation and phonon anomaly associated with strong p-f mixing effect of CeSb
Iwasa, K.; Hannan, A.; Kohgi, M.; Braden, M.; Mignot, J.-M.; Kitazawa, H.; Suzuki, T.
Applied Physics A: Materials Science and Processing, 2002

Spin excitations of the one-dimensional S = 1/2 Heisenberg antiferromagnet Yb₄As₃ under magnetic field
Kohgi, M.; Iwasa, K.; Mignot, J.-M.; F?k, B.; Hiess, A.; Gegenwart, P.; Lang, M.; Ochiai, A.; Aoki, H.; Suzuki, T.
Physica B: Condensed Matter, 2002

Neutron scattering studies of the one-dimensional quantum spin magnetism in Yb₄As₃
Kohgi, M.; Iwasa, K.; Mignot, J.-M.; Gukasov, A.; F?k, B.; Hiess, A.; Ochiai, A.; Aoki, H.
Applied Physics A: Materials Science and Processing, 2002

Direct Observation of the Modulation of the [Formula presented]-Electron Orbital State by Strong [Formula presented] Mixing in CeSb
Iwasa, K.; Hannan, A.; Kohgi, M.; Suzuki, T.
Physical Review Letters, 2002

Direct observation of the modulation of the 4f-electron orbital state by strong p-f mixing in CeSb
Iwasa, K.; Hannan, A.; Kohgi, M.; Suzuki, T.
Physical Review Letters, 2002

Staggered-field effect on the magnetic-field-induced magnetization of the one-dimensional antiferromagnet (formula presented)
Kazuaki Iwasa; Masahumi Kohgi; Arsen Gukasov; Jean-Michel Mignot; Naokazu Shibata; Akira Ochiai; Hidekazu Aoki; Takashi Suzuki, Magnetic properties in the charge-ordered phase of (formula presented) have been studied by polarized-neutron diffraction. It is revealed that one-dimensional (1D) chains of magnetic (formula presented) ions are formed by charge ordering below 290 K. The field-induced magnetic moment on the 1D chain under a field parallel to the chain behaves as that of a spin-1/2 1D Heisenberg antiferromagnet with a g factor (formula presented) In the case of a field perpendicular to the chain, we observed a pronounced enhancement below about 10 K. The observed enhancement of the field-induced magnetization is reproduced well by a theory which takes into account the staggered-field effect due to the Dzyaloshinsky-Moriya interaction within the 1D magnetic chain. © 2002 The American Physical Society.
Physical Review B - Condensed Matter and Materials Physics, 2002, [Reviewed]

Critical spin dynamics in the two-dimensional percolating Ising antiferromagnet, Rb2CocMg1-cF4
S Itoh; Y Kouchi; S Ikeda; K Iwasa; H Ikeda; MA Adams; R Kajimoto, We performed inelastic neutron-scattering experiments with high energy resolution, in order to investigate the critical spin dynamics in the two-dimensional (2D) Ising antiferromagnet, Rb2CoeMg1-cF4, with c = 0.6, 0.65, 0.7 and 1, above the percolation threshold c(p) (c(p) = 0.593 for a square lattice). First, we have confirmed the dynamical scaling for the homogeneous system (c = 1), and the observed dynamical critical exponent (z = 2.01 +/- 0.05) was very close to that obtained from recent numerical studies. Next, the observed spin dynamics in the dilute systems could be described by the temperature dependence expected by the standard scaling theory, the power of the, reduced temperature, however, the values of the exponents deviate from those predicted by the 2D Ising model and increase as c approaches to c, from the homogeneous limit. Also, the observed spin dynamics for c close cp was in a quantitatively good agreement with that predicted by the model for critical spin dynamics in a percolating Ising system, in which the nature of the spin dynamics is determined by the requirement to overcome, via thermal excitation, energy barriers to the overturning of the spins in domains resulting from the inhomogeneous geometry of the percolating network. Although we could not directly detect the difference in the functional form between that expected by the standard scaling theory and that predicted by the percolation model in the present experimental condition, we conclude, from the quantitative agreement, that the critical spin dynamics in Rb2CoeMg1-eF4 with e close to and just above c(p) is well described by the percolation model., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Oct. 2001

Imaging of electron density distribution of CeP under high pressure by single crystal SR X-ray experiments
T Shobu; Y Noda; K Iwasa; A Hannan; M Kohgi; N Ishimatsu; O Shimomura, PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Apr. 2001

Polarized-neutron study of one-dimensional magnetic response under magnetic field in the charge-ordered phase of Yb₄As₃
Iwasa, K.; Kohgi, M.; Gukasov, A.; Mignot, J.-M.; Shibata, N.; Ochiai, A.; Aoki, H.; Suzuki, T.
Journal of Magnetism and Magnetic Materials, 2001

Staggered field effect on the one-dimensional S = 1/2 antiferromagnet Yb₄As₃
Kohgi, M.; Iwasa, K.; Mignot, J.-M.; F?k, B.; Gegenwart, P.; Lang, M.; Ochiai, A.; Aoki, H.; Suzuki, T.
Physical Review Letters, 2001

One-Dimensional Magnetic State in the Charge-Ordered Phase of Yb4As3 Investigated by Polarized-Neutron Measurements (Proceedings of the 1st International Symposium on Advanced Science Research(ASR-2000), Advances in Neutron Scattering Research)
Iwasa Kazuaki; Kohgi Masahumi; Gukasov Arsen, Lead, Physical Society of Japan
Journal of the Physical Society of Japan, 2001, [Reviewed]

Spin Dynamics of the Quantum Spin System Yb4As3 under Magnetic Field (Proceedings of the 1st International Symposium on Advanced Science Research(ASR-2000), Advances in Neutron Scattering Research)
Kohgi Masahumi; Iwasa Kazuaki; Mignot Jean-Michel, Physical Society of Japan
Journal of the Physical Society of Japan, 2001, [Reviewed]

Magnetic Form Factor in UGe2 (Proceedings of the 1st International Symposium on Advanced Science Research(ASR-2000), Advances in Neutron Scattering Research)
Sagayama Hajime; Kuwahara Keitaro; Iwasa Kazuaki, Physical Society of Japan
Journal of the Physical Society of Japan, 2001, [Reviewed]

Crystal-lattice anomaly of CeSb under high pressure induced by magnetic polaron formation
A Hannan; K Iwasa; M Kohgi; T Suzuki, PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Jul. 2000

Magnetic structure of CeAs under high pressure
T Osakabe; M Kohgi; K Iwasa; M Kubota; H Yoshizawa; Y Haga; T Suzuki, Neutron diffraction experiments on CrAs revealed that the pressure versus temperature phase diagram and magnetic structures in the phase diagram are very similar to those of CeP. The difference is critical pressure values P-c, which are about 0.3 GPa in CeP and about 1.2 GPa in CeAs, and above which the long period magnetic structures composed of Gamma(7) and Gamma(8) Ce (0 0 1) planes appear. This is discussed in connection with the difference of their carrier numbers and the Gamma(8) P-f mixing effect. (C) 2000 Published by Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV
PHYSICA B-CONDENSED MATTER, Jun. 2000, [Reviewed]

Physics of low-carrier system detected by neutron and X-ray scattering: Ce-monopnictides case
M Kohgi; K Iwasa; T Osakabe, The origin of the unusual magnetic properties of Ce-monopnictide, CeX (X = P,As,Sb,Bi), whose carrier density is very low, is discussed on the basis of the physical picture obtained from recent neutron and X-ray scattering experiments. It is revealed that the unusual properties of the compounds originate from the appearance of T(8)-like Ce ions, the moment value of which is about 2 mu(B), among Ce ions with Gamma(7) crystal field ground state. The 2 mu(B) Ce ions appear in the form of ferromagnetic sheets of (0 0 1) planes, which form stacking magnetic structures of various sequences with sandwiching Gamma(7) Ce planes depending on the carrier density. The formation of the ferromagnetic sheets of 2 mu(B) Ce in the Gamma(7) Ce lattice is ascribed to the combined effects of strong p-f mixing and carrier localization due to the low-carrier density. (C) 2000 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV
PHYSICA B-CONDENSED MATTER, Jun. 2000, [Reviewed]

Crystal-lattice modulations associated with unusual magnetic structures in the low-carrier system CeSb
Iwasa, K.; Arakaki, Y.; Kohgi, M.; Suzuki, T.
Physica B: Condensed Matter, 2000

Magnetic states of Yb ions in the charge ordered phase of Yb₄As₃ determined by polarized-neutron scattering
Iwasa, K.; Kohgi, M.; Gukasov, A.; Mignot, J.-M.; Ochiai, A.; Aoki, H.; Suzuki, T.
Physica B: Condensed Matter, 2000

Polarized-neutron study on 4f-electron wave functions of magnetic-polaron state in CeP
Iwasa, K.; Kohgi, M.; Haga, Y.; Suzuki, T.; Kakurai, K.; Nishi, M.; Nakajima, K.; Link, P.; Gukasov, A.; Mignot, J.-M., The magnetic form factors of Ce ions in CeP have been studied by unpolarized and polarized neutron diffraction. The measured form factor in the type-I antiferromagnetic phase (H = 0 and T = 2 K) agrees with the calculation for a ・｡7 crystal-field pound state. On the contrary, the data at H = 3 T and T = 1.7 K (in the so-called 'phase I') and that at H = 5.5 T and T = 12 K (in 'phase III') indicate that the Ce ions with large moments appearing in these structures are in a strongly polarized state very close to the crystal-field state ・｡8. This result supports the view that a ・｡8-like wave function is stabilized by the formation of a magnetic-polaron state.
Journal of Physics and Chemistry of Solids, Sep. 1999, [Reviewed]

Evidence for crystal-lattice modulation due to spatially restricted enhancement of mixing effect in the low-carrier system CeSb
K Iwasa; Y Arakaki; M Kohgi; T Suzuki, In order to investigate the unusual magnetic properties of the low-carrier system CeSb, X-ray diffraction studies at low temperatures have been performed. Below the magnetic transition temperature of T-N = 17K, several X-ray satellite peaks and their temperature variations were observed, which indicate that the modulated structures of a crystal lattice coexist with the long-period magnetic structures in CeSb. The observed wave numbers of the lattice modulations and the satellite-peak intensities are explained by the periodical arrangement of short and long distances between magnetic layers. The short interlayer distance is due to enhancement of p-mixing effect which is spatially restricted within the ferromagnetic layers of Gamma(8)-like Ce ions appearing in the lattice of Gamma(7) Ce ions. The interlayer distance due to Gamma(8)-like state is shorter la 0.1% than that between normal Gamma(7) Ce layers., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Aug. 1999

X-ray diffraction study on thermal properties of crystal lattices in CeP and CeAs
K Iwasa; M Kohgi; H Ohsumi; K Tajima; T Takeuchi; Y Haga; A Uesawa; T Suzuki, X-ray diffraction studies at low temperatures have been performed in order to investigate thermal properties of crystal lattices in the low-carrier-density systems cerium monopnictides. CeP and CeAs show large crystal-lattice contractions with increasing temperatures up to about 120 K and 90 K, respectively. Due to the strong p-f mixing, the excited crystal field Gamma(s)-like state is expected to produce a shorter interatomic bond length between cerium ions and neighboring pnictogens than that realized by the Gamma(7) ground state. The experimental results of the lattice contractions at low temperatures are explained by the thermal average of these crystal field states., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Mar. 1999

Novel Magnetic Structure of the Low Carrier System CeP and CeAs under External Fields
OSAKABE Toyotaka; KOHGI Masahumi; IWASA Kazuaki; KAKURAI Kazuhisa; MIGNOT Jean-Michel; GONCHARENKO Igor; OKAYAMA Yasushi; TAKAHASHI Hiroki; MORI Nobuo; KUBOTA Masato; YOSHIZAWA Hideki; HAGA Yoshinori; SUZUKI Takashi; 著者名無し; 著者名無し, 社団法人応用物理学会
JJAP series, Feb. 1999, [Reviewed]

Polarized-Neutron and X-ray Diffraction Studies of the Low-Carrier System Cerium Monopnictides
IWASA Kazuaki; KOHGI Masahumi, Lead, 社団法人応用物理学会
JJAP series, Feb. 1999, [Reviewed]

Low Energy Excitations in the Low-Carrier Heavy-Electron System Yb_4As_3
KOHGI Masahumi; IWASA Kazuaki; MIGNOT Jean-Michel; PYKA Niels; KADOWAKI Hiroaki; OCHIAI Akira; AOKI Hidekazu; SUZUKI Takashi; 著者名無し, 社団法人応用物理学会
JJAP series, Feb. 1999, [Reviewed]

Appearance of ferromagnetism in CeP at high pressure
Goncharenko, I.N.; Link, P.; Mignot, J.-M.; Kohgi, M.; Iwasa, K.; Haga, Y.; Suzuki, T.
Physica B: Condensed Matter, 1999

Magnetic excitations in the charge ordered state of Yb₄As₃ and Yb₄(As_0.6P_0.4)₃
Kohgi, M.; Iwasa, K.; Mignot, J.-M.; Pyka, N.; Ochiai, A.; Aoki, H.; Suzuki, T.
Physica B: Condensed Matter, 1999

Strongly coupled charge-density wave transition in single-crystal Lu₅Ir₄Si₁₀
Becker, B.; Patil, N.G.; Ramakrishnan, S.; Menovsky, A.A.; Nieuwenhuys, G.J.; Mydosh, J.A.; Kohgi, M.; Iwasa, K.
Physical Review B - Condensed Matter and Materials Physics, 1999

Magnetoelastic properties of CeP studied by thermal expansion and magnetostriction
T Takeuchi; K Iizuka; K Iwasa; M Kohgi; Y Haga; T Suzuki, Magnetoelastic properties of a single crystal of CeP have been investigated by magnetostriction and thermal expansion measurements. The longitudinal and transverse magnetostriction with the field along the [001] direction show an abrupt decrease in length following the appearance of the ferromagnetically ordered planes with the Gamma(8) Ce moments. Moreover, iso-field thermal expansion along both directions show a large increase of the length at the temperature where the ferromagnetic-paramagnetic transition of the Gamma(8) Ce moments takes place. Such large length changes can be understood by the p-f mixing effect which has been used successfully to explain the magnetic phase diagram of CeP., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Jun. 1998

Spin dynamics of the low-carrier heavy-electron system Yb₄As₃
Kohgi, M.; Iwasa, K.; Mignot, J.-M.; Ochiai, A.; Suzuki, T.
Journal of Magnetism and Magnetic Materials, 1998

X-ray diffraction studies of lattice properties in CeX (X = P and As) and Yb₄As₃
Iwasa, K.; Kohgi, M.; Nakajima, N.; Yoshitake, R.; Hisazaki, Y.; Osumi, H.; Tajima, K.; Wakabayashi, N.; Haga, Y.; Ochiai, A.; Suzuki, T.; Uesawa, A.
Journal of Magnetism and Magnetic Materials, 1998

Magnetic Phase Diagram of CeP under High Pressure
KOHGI M.; OSAKABE T.; IWASA K.; MIGNOT J. M.; GONCHARENKO I. N.; LINK P.; OKAYAMA Y.; TAKAHASHI H.; MORI N.; HAGA Y.; SUZUKI T., Neutron scattering experiments under high pressure revealed the existence of quite novel magnetic structures in CeP at low temperatures. They are characterized by the formation of a lattice of 2μ_B Ce ferromagnetic layers, inside of which Γ₇ Ce layers are sandwiched and orders antiferromagnetically rather independently. The period of the 2μ_B Ce lattice becomes shorter with increasing pressure, and at the pressures above 1. 7 GPa, the magnetic structures become quite similar to those seen in CeSb at ambient pressure. It indicates that the electronic structure of CeP becomes closer to that of CeSb under high pressure. The present results provide useful information to understand common physics in the typical low-carrier system Ce-monopnictides., The Japan Society of High Pressure Science and Technology
The Review of High Pressure Science and Technology, 1998

Novel magnetic structures of the low-carrier system CeP under high pressure
T Osakabe; M Kohgi; K Iwasa; N Nakajima; JM Mignot; IN Goncharenko; Y Okayama; H Takahashi; N Mori; Y Haga; T Suzuki, The results of neutron scattering experiments on the low-carrier system CeP under high pressure up to 1.7 GPa are presented. The magnetic structures derived from the scattering patterns at various pressures at low temperatures are similar to those of CeP under magnetic field, forming the periodic stacking of the double Gamma(8) Ce (0 0 1) planes with sandwiching the Gamma(7) Ce (0 0 1) planes. The difference is a wide and systematic change of the period of the stacking of Gamma(8) Ce (001) planes with changing pressure. These results support strongly the magnetic polaron model for the unusual properties of CeP., ELSEVIER SCIENCE BV
PHYSICA B-CONDENSED MATTER, Feb. 1997, [Reviewed]

One-dimensional antiferromagnetic coupling in the low-carrier heavy-electron system The role of charge ordering
Kohgi, M.; Iwasa, K.; Mignot, J.
Physical Review B - Condensed Matter and Materials Physics, 1997

Magnetic excitations and spin correlations in two-dimensional percolating Ising antiferromagnets
K Iwasa; H Ikeda; KH Andersen; RS Eccleston, The magnetic excitations in two-dimensional percolating Ising-type antiferromagnets, Rb2CocMg1-cF4 (c = 0.60 and 0.70), were studied by pulsed-neutron scattering. The peaks due to Ising-cluster excitations were clearly observed far above TN. Their intensities exist even at 5T(N) and 2T(N) for c = 0.60 and 0.70, respectively. This reveals that the characteristic time of the spin correlation in percolating networks is much longer than that of neutrons traveling through the systems, and, therefore, the spins can provide molecular fields at the neighboring sites, even in paramagnetic regions., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Apr. 1996

SPIN DYNAMICS IN AN ISING-LIKE QUANTUM SPIN CHAIN WITH NONMAGNETIC IMPURITIES
S ITOH; H IKEDA; D SUGIMOTO; K IWASA; RS ECCLESTON, Neutron inelastic-scattering experiments on an Ising-like quantum antiferromagnetic chain with nonmagnetic impurities, CsCocMg1-cCl3 (c=1, 0.95, 0.9, 0.85, 0.6 and 0.4), were performed. The concentration dependence of the spin dynamics showed that although the solitons and the spin-wave continuum state were stable for a small amount of nonmagnetic impurities, they vanished at c=0.8. We also observed the coexistence of Ising-cluster excitations and intra-cluster excitations at low temperatures. These results can be well interpreted by a theory incorporated with next nearest-neighbor interactions in the chain., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Mar. 1995

Spin correlations in percolating networks with fractal geometry
Ikeda, H.; Iwasa, K.; Fern; ez-Baca, J.A.; Nicklow, R.M.
Physica B: Physics of Condensed Matter, 1995

Localized magnons in a two-dimensional mixed antiferromagnet
Iwasa, K.; Ikeda, H.
Physica B: Physics of Condensed Matter, 1995

HIGH-RESOLUTION INELASTIC NEUTRON-SCATTERING FROM RBMNCMG1-CF3 (C=0.10 AND 0.15) UNDER MAGNETIC-FIELDS
K IWASA; KH ANDERSEN; M TAKAHASHI; H IKEDA, Recently, a high-resolution inelastic neutron spectrometer equipped with a superconducting magnet has been installed at the pulsed spallation neutron source (KENS) at the National Laboratory for High Energy Physics (KEK). For the first experiment using this spectrometer system, we investigated inelastic neutron scattering from diluted Heisenberg magnetic systems, RbMncMg1-cF3 (c=0.10 and 0.15) at 1.5 K with applied magnetic fields. Magnetic excitations in finite-size clusters were observed due to the low concentration of spins localized at the manganese ions. The observed spectra were compared with calculations which were performed by diagonalizing the Hamiltonian. Extending the number of spins in a cluster up to five, good agreement with calculations was obtained for both excitation energies and scattering intensities., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Aug. 1994

PRESSURE-INDUCED LONG-PERIOD MAGNETIC-STRUCTURE IN LAYERED ANTIFERROMAGNETS RB2MNF4 AND CS2MNF4
K IWASA; M NISHI; H IKEDA; J SUZUKI, The magnetic structure along the axial direction in the layered antiferromagnets, Rb2MnF4 and CS2MnF4, was studied under hydrostatic pressure by using neutron scattering techniques. These compounds revealed predominantly antiferromagnetic stacking of magnetic layers at ambient pressure below their Neel temperatures. Upon applying pressure, however, the stacking changed remarkably; the ferromagnetic stacking became dominant and antiferromagnetic stacking completely vanished. Besides these two dominant peaks, several small peaks, which correspond to longer-period stacking, were also observed. These results are qualitatively explained by taking the competing interplanar interactions into consideration., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, May 1994

Fracton excitations in a diluted Heisenberg antiferromagnet near the percolation threshold: RbMn_0.39Mg_0.61F₃
Ikeda, H.; Fern; ez-Baca, J.A.; Nicklow, R.M.; Takahashi, M.; Iwasa, K.
Journal of Physics: Condensed Matter, 1994

LATTICE MODULATIONS INDUCED BY MAGNETOELASTIC EFFECT IN CRYSTALS CONTAINING RARE-EARTH ELEMENTS
K IWASA; N WAKABAYASHI; T TAKABATAKE; H FUJII; T SHIGEOKA, Lattice modulations associated with magnetic order in Tm and Er were investigated by means of X-ray diffraction. Satellite peaks at wave vectors (0 0 2q(0)) and (0 0 4q(0)) were observed in Tm where q(0) is the fundamental wave number specifying the modulations of the magnetic moment along the hexagonal c-axis. The modulation amplitude, the atomic displacement along the c-axis, was estimated to be of the order of 10(-3) Angstrom. No peak was detected at q(0). Peaks for 2q(0) and 4q(0) were observed also in Er. The amplitude of the 2q(0) modulations decreased with decreasing temperature below 30 K. A model based on the magnetoelastic interactions was constructed to calculate these amplitudes of lattice modulations. It involves the elastic, exchange and crystal field energies. The latter two magnetic energies were assumed to vary with the interatomic distance. This model, combined with the temperature variations of the magnetic moment, was found to reproduce the temperature dependence of the lattice modulations in Tm and Er. X-ray diffraction measurements were also made for UPdIn and NdCo2Si2. The magnetoelastic effects in these materials appear to be much weaker than those in Tm and Er., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Jan. 1994

SELF-SIMILARITY OF MAGNETIC ORDER IN 2-DIMENSIONAL PERCOLATING ANTIFERROMAGNETS
H IKEDA; K IWASA; KH ANDERSEN, The intensity distribution of the magnetic elastic scattering of neutrons near the superlattice position, in two-dimensional diluted Ising antiferromagnets, Rb2CocMg1-cF4 (c = 0.60, 0.65 and 0.70), reveals direct experimental evidence of the self-similarity of the magnetic order in a percolating magnetic system. The observed fractal dimension is 1.95 +/- 0.07, which is in accord with a numerically estimated value of 1.896. Evidence for a crossover from a self-similar fractal structure to a homogeneous structure is also presented., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Nov. 1993

X-RAY DIFFUSE-SCATTERING IN [PT(EN)2][PTCL2(EN)2](CLO4)4
K IWASA; N WAKABAYASHI; M SAKAI; N KURODA; Y NISHINA, The halogen-bridged transition metal complex [Pt(en)2][PtCl2(en(2](ClO4)4 has a quasi-one dimensional structure with Pt ions forming chains along the b-axis. The valence of the Pt ions can have two possible values, II and IV, and is disordered. Diffuse X-ray scattering was found for wavevectors around (0 2n + 1 0). The intensity distribution along the (0 1 0) was very narrow, while that for wavevectors perpendicular to (0 2n + 1 0) showed clearly the existence of a short range order between the valence sequences of neighboring chains. A strong correlation has been found between the chain at the origin and one at the second neighbor position along the c-axis. The results were analyzed in terms of interchain interactions., PHYSICAL SOCIETY JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, Oct. 1992

先端研究と人材育成で地域・社会に貢献する 茨城大学原子科学研究教育センター設立　　　　　　　　　　　　　　　
岩佐和晃
一般財団法人総合科学研究機構機関誌「CROSS T&T」, Jul. 2024
Lead

Successive phase transitions of Kondo semimetal Ce₃Ir₄Sn₁₃
中里晟也; 岩佐和晃; 橋本大輔; 塩澤真未; 桑原慶太郎; 中尾裕則; 佐賀山基; 石角元志; 大原高志; 中尾朗子; 宗像孝司; 鬼柳亮嗣; DAMAY F.; MIGNOT J.-M.
日本物理学会講演概要集(CD-ROM), 2020

Successive phase transitions of Kondo semimetal Ce₃Ir₄Sn₁₃
岩佐和晃; 中里晟也; 橋本大輔; 塩澤真未; 桑原慶太郎; 中尾裕則; 佐賀山基; 石角元志; 大原高志; 中尾朗子; 宗像孝司; 鬼柳亮嗣; DAMAY F.; MIGNOT J.-M.; 河村聖子; 村井直樹; 中島健次
日本物理学会講演概要集(CD-ROM), 2020

Obituary "In memoriam: Nobuyoshi Wakabayashi (1938–2017)"
Kazuaki Iwasa; Sunil K. Sinha; William Kamitakahara; Jaime Fernandez-Baca; Keisuke Tajima & Kazuhisa Kakurai
Neutron News, 27 Apr. 2018
Lead

TbB₆における磁気-構造相転移の再検証
岩佐和晃; 伊賀文俊; 茂吉武人; 中尾朗子; 大原高志
日本物理学会講演概要集(CD-ROM), 2018

4f2配位系PrIr2Zn20における反強多極子秩序
鬼丸孝博; 岩佐和晃
日本中性子科学会誌「波紋」, 10 Nov. 2017, [Reviewed]

Sc置換LaCoO₃における磁化と体積磁歪-スピン状態転移近傍に現れる励起子絶縁体の候補物質としての検討-
富安啓輔; 伊藤菜緒子; 岡崎竜二; 高橋佑生; 小野寺貢; 岩佐和晃; 岩佐和晃; 野島勉; 青山拓也; 大串研也; 石川喜久; 神山崇; 神山崇; 神山崇; 石原純夫
日本物理学会講演概要集(CD-ROM), 2017

連載講座 中性子散乱による原子・分子のダイナミクスの観測「VI-1 希土類金属系における電子自由度と磁気励起スペクトル」
岩佐和晃
RADIOISOTOPES, 15 Jun. 2016, [Reviewed], [Invited]

9aBJ-9 X-ray and neutron scattering study on single crystals of R_3Co_4Sn_<13> (R = Ce, La)
Otomo Y.; Iwasa K.; Tomiyasu K.; Ohira-Kawamura S.; Nakajima K.; Sagayama R.; Nakao H.; Kumai R.; Murakami Y.
Meeting abstracts of the Physical Society of Japan, 22 Aug. 2014

9pBC-4 Inelastic neutron scattering study of spin-orbit fluctuations in frustrated heavy-fermion metal LiV_2O_4
Tomiyasu K.; Iwasa K.; Ueda H.; Niitaka S.; Takagi H.; Ohira-Kawamura S.; Kikuchi T.; Nakajima K.; Yamada K.
Meeting abstracts of the Physical Society of Japan, 22 Aug. 2014

PrT₂Zn₂₀(T=Os,Ir)における磁気励起スペクトル
岩佐和晃; 大友優香; 河村聖子; 中島健次; 鬼丸孝博; 松本圭介; 脇舎和平; 高畠敏郎
日本物理学会講演概要集, 22 Aug. 2014

Neutron magnetic scattering study in manganite thin film system
H. Nakao; H. Yamada; A. Sawa; K. Iwasa; J. Okamoto; T. Sudayama; Y. Yamasaki; Y. Murakami
SOLID STATE COMMUNICATIONS, May 2014

30pAB-3 Installation of newly proposed polarized neutron spectrometer POLANO in J-PARC II
Yokoo T.; Ohoyama K.; Itoh S.; Iwasa K.; Kaneko N.; Okawara M.; Suzuki J.; Muroya T.; Sugai S.; Aizawa K.
Meeting abstracts of the Physical Society of Japan, 05 Mar. 2014

27aCM-10 Light impurity substitution effect in EuCoO_3
Tomiyasu K.; Nara S.; Yagi H.; Iwasa K.
Meeting abstracts of the Physical Society of Japan, 05 Mar. 2014

27pBE-4 Metastable superlattices in the paramagnetic phases of RB_6(R = Gd, Tb, Dy)
Iwasa K.; Igarashi R.; Amano M.; Iga F.
Meeting abstracts of the Physical Society of Japan, 05 Mar. 2014

f電子四極子系PrT₂Zn₂₀における磁気励起の極低温測定
岩佐和晃; 大友優香; 河村聖子; 中島健次; 鬼丸孝博; 松本圭介; 脇舎和平; 高畠敏郎
日本中性子科学会年会講演概要集, 2014

27aKE-4 Installation of newly proposed polarized neutron spectrometer POLANO in J-PARC
Yokoo T.; Ohoyama K.; Itoh S.; Suzuki J.; Sato T.J.; Iwasa K.; Kimura H.; Kaneko N.; Okawara M.; Nanbu Y.
Meeting abstracts of the Physical Society of Japan, 26 Aug. 2013

X-ray scattering study on superlattice structure in DyB_6
Iwasa K.; Amano M.; Nakao H.; Murakami Y.
Meeting abstracts of the Physical Society of Japan, 26 Aug. 2013

27aPS-67 Crystal Field Splitting Schemes of PrT_2Zn_<20> (T=Ru,Rh,Ir)
Kobayashi H.; Iwasa K.; Tomiyasu K.; Nagasawa N.; Matsumoto K. T.; Onimaru T.; Takabatake T.
Meeting abstracts of the Physical Society of Japan, 26 Mar. 2013

26pXT-14 Superlattice structure in a reentrant metal-nonmetal transition system Pr_<1-x>Ce_xRu_4P_<12>
Sato T.; Iwasa K.; Saito K.; Nakao H.; Murakami Y.; Itoh S.; Yokoo T.; Kawana D.
Meeting abstracts of the Physical Society of Japan, 26 Mar. 2013

Electronic Interactions in f-electron Systems and Neutron Scattering Spectra
岩佐 和晃
波紋, Nov. 2012

18aPSA-16 Magnetic properties of Fe_<1+δ>Sb
Choi S-C.; Hiraka H.; Ohoyama K.; Yamaguchi Y.; Nara S.; Iwasa K.; Yamada K.
Meeting abstracts of the Physical Society of Japan, 24 Aug. 2012

21aPSB-13 Search for electron-doped LaCoO_3 system and its evaluation by magnetization and resistivity measurements
Koyama S.; Watahiki M.; Iwasa K.; Nakao H.; Tomiyasu K.
Meeting abstracts of the Physical Society of Japan, 24 Aug. 2012

Present Status of Neutron Scattering Instruments of Tohoku University Installed at JRR-3
岩佐 和晃; 平賀 晴弘; 大河原 学
波紋, Aug. 2012

Development of a non-adiabatic two-coil spin flipper for a polarised thermal neutron diffractometer with a ³He spin filter
Kenji Ohoyama; Kenji Tsutsumi; Takashi Ino; Haruhiro Hiraka; Yasuo Yamaguchi; Hiroshi Kira; Hiroshi Kira; Takayuki Oku; Yoshifumi Sakaguchi; Yoshifumi Sakaguchi; Yasushi Arimoto; Wei Zhang; Hisamichi Kimura; Kazuaki Iwasa; Masayasu Takeda; Jun Ichi Suzuki; Jun Ichi Suzuki; Kazuyoshi Yamada; Kazuhisa Kakurai
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 11 Jul. 2012

25pCL-14 Progress of Polarisation Analysis Neutron Spectrometer Project in J-PARC
Ohoyama K.; Iwasa K.; Yokoo Y.; Itoh S.; Tomiyasu K.; Matusura M.; Hiraka H.; Fujita M.; Kimura H.; Sato T.; Sato T.J.; Arima T.; Ino T.; Kira H.; Sakaguchi Y.; Oku T.; Arimoto Y.; Suzuki J.; Shimizu H.M.; Takeda M.; Kaneko K.; Hino M.; Muto G.; Nojiri H.
Meeting abstracts of the Physical Society of Japan, 05 Mar. 2012

27aYC-5 A neutron scattering study on a localized and an itinerant nature related to f^2 electron states of PrCu_4t (T=Au and Ag)
Kobayashi H.; Saito K.; Tomiyasu K.; Iwasa K.; Kawana D.; Zhang S.; Ishikawa Y.; Mignot J. -M.; Andre G; Kolesnikov A. I.; Savich A. T.; Granroth G. E.
Meeting abstracts of the Physical Society of Japan, 05 Mar. 2012

26pYH-3 Observation of the orbital-wave excitation in YVOs using a chopper spectrometer for inelastic neutron scattering
Kawana D.; Murakami Y.; Yokoo T.; Itoh S.; Savich A. T.; Granroth G. E.; Ikeuchi K.; Nakao H.; Iwasa K.; Fukuta R.; Miyasaka S.; Tajima S.; Ishihara S.; Tokura Y.
Meeting abstracts of the Physical Society of Japan, 05 Mar. 2012

25aPS-55 Magnetic and transport properties in light electron doped LaCoO_3
Watahiki M.; Tomiyasu K.; Iwasa K.; Nakao H.
Meeting abstracts of the Physical Society of Japan, 05 Mar. 2012

24pYB-3 The Study on Successive Metal-nonmetal Transition on Pr_<1-x>Ce_xRu_4P_<12> by Observation of Crystal Field Levels
Saito K.; Iwasa K.; Mignot J.-M.
Meeting abstracts of the Physical Society of Japan, 05 Mar. 2012

24pYB-5 Totally symmetric ordered phase of PrFe_4P_<12> investigated by neutron scattering
Iwasa K; Hao Lijie; Kohgi M; Kuwahara K; Mignot J.-M; Sugawara H; Aoki Y; Matsuda T. D; Sato H
Meeting abstracts of the Physical Society of Japan, 05 Mar. 2012

ペロブスカイト型バナジウム酸化物の磁気・軌道秩序に対するランダムネス効果
宮坂茂樹; 福田龍一郎; 逸見和宏; 佐々木直哉; 田島節子; 川名大地; 池内和彦; 山崎裕一; 中尾朗子; 中尾裕則; 熊井玲児; 村上洋一; 岩佐和晃
PFシンポジウム要旨集, 2012

Magnetic ordering of PrxFe4Sb12(x<1)　　　　　　　　　　　　　　　
K. Iwasa; T. Orihara; K. Saito; K. Tomiyasu; Y. Murakami; H. Sugawara; K. Kuwahara; H. Kimura; R. Kiyanagi; Y. Ishikawa; Y .Noda; Y. Aoki; H. Sato; M. Kohgi
Activity Report on Neutron Scattering Research: Experimental Reports, Oct. 2011

21aGD-1 Randomness and Cr substitution effects on spin/orbital order in perovskite RVO_3
Fukuta R.; Henmi K.; Sasaki N.; Miyasaka S.; Tajima S.; Kawana D.; Ikeuchi K.; Yamasaki Y.; Nakao A.; Nakao H.; Murakami Y.; Iwasa K.
Meeting abstracts of the Physical Society of Japan, 24 Aug. 2011

21pGC-3 The Attempt to Observe Multipole Ordering in Pr(Ru_<1-x>Rh_x)_4P_<12> using Synchrotron X-ray
Saito K.; Iwasa K.; Nakao H.; Murakami Y.; Podlesnyak A.; Ehlers G.
Meeting abstracts of the Physical Society of Japan, 24 Aug. 2011

23pGP-10 Observation of Magnetic Excitation in MnP using High Resolution Chopper Spectrometer
Yano S; Akimitsu J; Itoh S; Yokoo T; Satoh S; Kawana D; Endoh Y; Iwasa K; Wakimoto S; Metoki N; Kakurai K
Meeting abstracts of the Physical Society of Japan, 24 Aug. 2011

22aPS-57 Magnetization measurements of LaCoO_3 with diluted impurity
Kubota Y.; Tomiyasu K.; Iwasa K.
Meeting abstracts of the Physical Society of Japan, 24 Aug. 2011

23aPS-109 A crystal-field level scheme and magnetic ordering of a heavy electron system PrCu_4Au
Kobayashi H.; Saito K.; Tomiyasu K.; Iwasa K.; Zhang S.; Ishikawa Y.
Meeting abstracts of the Physical Society of Japan, 24 Aug. 2011

23pGB-3 Study of LaCoO_3 system with lightly doped impurities by inelastic neutron scattering and magnetization measurements
Tomiyasu Keisuke; Kubota Yuuki; Stuhr Uwe; Iwasa Kazuaki; Yamada Kazuyoshi
Meeting abstracts of the Physical Society of Japan, 24 Aug. 2011

22pJA-2 Progress of Polarisation Analysis Neutron Spectrometer Project in J-PARC
Ohoyama K.; Iwasa K.; Yokoo Y.; Itoh S.; Hiraka H.; Fujita M.; Matusura M.; Kimura H.; Tomiyasu K.; Sato T.; Sato T. J.; Arima T.; Ino T.; Kira H.; Sakaguchi Y.; Oku T.; Arimoto Y.; Suzuki J.; Shimizu H. M.; Takeda M.; Kaneko K.; Hino M.; Muto G.; Nojiri H.
Meeting abstracts of the Physical Society of Japan, 24 Aug. 2011

25aTN-6 Present Status of Polarized Spectrometer Project in J-PARC
Ohoyama K.; Iwasa K.; Itoh S.; Yokoo Y.; Hiraka H.; Fujita M.; Matusura M.; Sato T.; Horigane K.; Sato T. J.; Tomiyasu K.; Arima T.; Ino T.; Kira H.; Sakaguchi K.; Oku T.; Arimoto Y.; Suzuki J.; Shimizu H. M.; Takeda M.; Kaneko K.; Hino M.; Muto G.; Nojiri H.
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2011

26pED-4 Neutron scattering study on the weak magnetism of Pr_xFe_4Sb_<12>
Orihara T.; Iwasa K.; Tomiyasu K.; Murakami Y.; Sugawara H.; Kuwahara K.; Tanaka K.; Saito T.; Tatsuoka S.; Iwasa K.; Watanabe M.; Aoki Y.; Sato H.; Kohgi M.
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2011

26pHF-10 Observation of Magnetic Excitation in MnP using High Resolution Chopper Spectrometer
Yano S; Akimitsu J; Itoh S; Yokoo T; Satoh S; Kawana D; Endoh Y; Iwasa K; Wakimoto S; Metoki N; Kakurai K
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2011

27pHF-3 Study of one-dimensional quantum spin system Rb_2Cu_2MO_3O<12> by inelastic neutron scattering and magnetic susceptibility measurements
Tomiyasu K.; Ambai H.; Iwasa K.; Masuda T.; Wakimoto S.; Kajimoto R.; Nakamura M.; Inamura Y.; Arai M.
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2011

25aPS-102 Crystal-field level schemes of PrT_2Zn_<20>(T=Ru and Ir)
Kobayashi H.; Iwasa K.; Tomiyasu K.; Matsumoto K.; Onimaru T.; Takabatake T.
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2011

25aPS-119 Moltipolar ordering in cubic NdPd_3S_4 III
Watahiki M.; Matsuoka E.; Nakamura S.; Nojima T.; Ohoyama K.; Iwasa K.; Tanigaki K.; Aoki H.; Onodera H.
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2011

25pPSB-67 Neutron scattering and magnetization measurements of diluted hole doped system (La_<1-x>Sr_x)CoO_3
Kubota Y.; Koyama S.; Tomiyasu K.; Iwasa K.; Uwe Stuhr; Kaneko K.; Ikeda S.; Umeyama N.
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2011

27pED-1 Large negative magnetoresistance in superlattice (LaMnO_3)_2(SrMnO_3)_2
Nakao H; Yamada H; Iwasa K; Yamasaki Y; Murakami Y; Sawa A
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2011

26pED-7 The study of f electron order in Pr(Ru_<0.97>Rh_<0.03>)_4P_<12> using resonant x-ray scattering
Saito K; Iwasa K; Nakao H; Murakami Y
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2011

26pEF-11 Spin-orbital order and randomness effect in perovskite type vanadium oxides II
Fukuta R; Henmi K; Miyasaka S; Tajima S; Kawana D; Ikeuchi K; Yamasaki Y; Nakao A; Nakao H; Murakami Y; Iwasa K
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2011

Educational activities for neutron sciences
平賀 晴弘; 岩佐 和晃; 大山 研司
Hamon, Feb. 2011

立方晶NdPd₃S₄の多極子物性 III
綿引正倫; 松岡英一; 中村慎太郎; 野島勉; 大山研司; 岩佐和晃; 谷垣勝己; 青木晴善; 小野寺秀也
日本物理学会講演概要集, 2011

ペロブスカイト型V酸化物の磁気・軌道秩序とランダムネス効果 II
福田龍一郎; 逸見和宏; 宮坂茂樹; 田島節子; 川名大地; 池内和彦; 山崎裕一; 中尾朗子; 中尾裕則; 村上洋一; 岩佐和晃
日本物理学会講演概要集, 2011

Molecular spin-liquid state in the spin-32 frustrated spinel HgCr ₂O₄
Tomiyasu, K.; Ueda, H.; Matsuda, M.; Yokoyama, M.; Iwasa, K.; Yamada, K.
Physical Review B - Condensed Matter and Materials Physics, 2011, [Reviewed]

Single-crystal neutron diffraction study of filled skutterudite compound PrFe_4P<12> under 10GPa
OSAKABE Toyotaka; YAMAUCHI Hiroki; KUWAHARA Keitaro; IWASA Kazuaki; AOKI Yuji; SATO Hideyuki; KOHGI Masahumi
高圧討論会講演集, 11 Oct. 2010

24aPS-24 Powder neutron scattering study of pyrochlore-type iridate Nd_2Ir_2O_7 with metal-insulator transition
Tomiyasu K.; Watahiki M.; Iwasa K.; Matsuhira K.; Wakeshima M.; Hinatsu Y.; Takagi S.
Meeting abstracts of the Physical Society of Japan, 18 Aug. 2010

25pPSA-67 Observation of Magnetic Diffuse Scattering of Fe-Alloys by Polarized Neutron
Tsutsumi K.; Ohoyama K.; Hiraka H.; Yamaguchi Y.; Ino T.; Kira H.; Sakaguchi K.; Oku T.; Arimoto Y.; Takeda M.; Suzuki J.; Iwasa K.; Yamada K.; Kakurai K.
Meeting abstracts of the Physical Society of Japan, 18 Aug. 2010

23pPSB-11 Neutron scattering study on the magnetism of the skutterudite Pr_xFe_4Sb_<12>
Orihara T.; Iwasa K.; Murakami Y.; Sugawara H.; Kuwahara K.; Tanaka K.; Saito T.; Tatsuoka S.; Iwasa K.; Watanabe M.; Aoki Y.; Sato H.; Kohgi M.
Meeting abstracts of the Physical Society of Japan, 18 Aug. 2010

23pPSB-10 Single-crystal neutron diffraction study of filled skutterudite PrFe_4P_<12> under 10 GPa
Osakabe T.; Yamauchi H.; Kuwahara K.; Iwasa K.; Aoki Y.; Sato H.; Kohgi M.
Meeting abstracts of the Physical Society of Japan, 18 Aug. 2010

24aWZ-13 Present Status of Polarised Neutron Diffraction Experiments in Tohoku Univ.
Ohoyama K.; Tsutsumi K.; Hiraka H.; Ino T.; Kira H.; Sakaguchi K.; Oku T.; Arimoto Y.; Takeda M.; Suzuki J.; Horigane K.; Iwasa K.; Wu F.; Kubota T.; Mizukami S.; Miyazaki T.; Yamada K.; Kakurai K.
Meeting abstracts of the Physical Society of Japan, 18 Aug. 2010

24pWZ-3 High Resolution Chopper Spectrometer at J-PARC
Yokoo T.; Itoh S.; Sato T. J.; Satoh S.; Yano S.; Kawana D.; Suzuki J.; Ueno K.; Kuwahara K.; Kamiyama T.; Iwasa K.; Ohoyama K.; Kawamura Y.; Asami T.; Sugiura R.
Meeting abstracts of the Physical Society of Japan, 18 Aug. 2010

25pPSA-52 Powder neutron and x-ray scattering study of one-dimensional quantum spin frustrated system (Rb_<1-x>CS_x)_2Cu_2Mo_3O_<12>
Anbai H; Tomiyasu K; Nakao A; Nakao H; Kaneko K; Osakabe T; Iwasa K
Meeting abstracts of the Physical Society of Japan, 18 Aug. 2010

23pPSB-9 Magnetic field and temperature dependence of synchrotron x-ray scattering from multipole ordering phase of Pr(Ru_<1-x>Rh_x)_4P_<12>
Saito K; Iwasa K; Hao L; Nakao H; Murakami Y
Meeting abstracts of the Physical Society of Japan, 18 Aug. 2010

20aPS-30 Application of Polarized Neutron by ^3He Filter Technique for Condensed-Matter Physics : Development of Spin Control Devices
Tsutsumi K.; Ohoyama K.; Hiraka H.; Yamaguchi Y; Ino T.; Oku T.; Sakaguchi K.; Kira H.; Arimoto Y.; Takeda M.; Suzuki J.; Iwasa K.; Yamada K.; Kakurai K.
Meeting abstracts of the Physical Society of Japan, 01 Mar. 2010

21pGD-3 Neutron diffraction study of Ce_xLa_<1-x>B_6 (x=1.0, 0.7) using short-wavelength neutrons
Kuwahara K.; Iwasa K.; Kohgi M.; J. Robert; Mignot J. -M.; Gukasov A.; Sera M.; Iga F.
Meeting abstracts of the Physical Society of Japan, 01 Mar. 2010

23pHT-2 Construction of High Resolution Chopper Spectrometer
Itoh S.; Yokoo T.; Sato T. J.; Yano S.; Satoh S.; Suzuki J.; Ueno K.; Kuwahara K.; Iwasa K.; Kamiyama T.; Yamamuro O.; Ohoyama K.; Otomo T.; Endoh Y.; Akimitsu J.; Kuroda S.; Sato K.; Nasu K.; Iwano K.; Oohara Y.; Yoshizawa H.; Kawamura Y.; Asami T.; Sugiura R.
Meeting abstracts of the Physical Society of Japan, 01 Mar. 2010

一次元量子スピンフラストレート系(Rb_1-xCs_x)₂Cu₂Mo₃O₁₂の粉末中性子・X線散乱による研究
安倍弘; 富安啓輔; 中尾朗子; 中尾裕則; 金子耕士; 長壁豊隆; 岩佐和晃
日本物理学会講演概要集, 2010

Structural modulation and multipolar ordering in the metal-nonmetal compounds Pr(Ru1-xRhx)(4)P-12
C. Laulhe; K. Saito; K. Iwasa; H. Nakao; Y. Murakami
INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009), 2010

25aPS-9 Pr(Ru_<1-x>Rh_x)_4P_<12>(x=0.01,0.03,0.05)単結晶試料による金属-非金属転移の研究(領域8ポスターセッション(f電子系等),領域8,強相関系:高温超伝導,強相関f電子系など)
斉藤 耕太郎; Laulhe C.; 岩佐 和晃; 村上 洋一; Khuong H. K.; 谷垣 勝己
日本物理学会講演概要集, 18 Aug. 2009

27pRE-5 幾何学的フラストレート系GeCo_2O_4の単結晶中性子非弾性散乱によるスピン励起測定(フラストレーション系(スピネル・パイロクロア・2次元系),領域3,磁性,磁気共鳴)
富安 啓輔; 富永 あやか; 原 茂生; 佐藤 博彦; 渡辺 忠孝; 池田 伸一; 岩佐 和晃; 山田 和芳
日本物理学会講演概要集, 18 Aug. 2009

25aRL-2 Magnetic excitation in Ba_2Mg_2Fe_<12>O_<22> observed by inelastic neutron-scattering
Okuyama D.; Kida N.; Iwasa K.; Ishiwata S.; Taguchi Y.; Arima T.; Tokura Y.
Meeting abstracts of the Physical Society of Japan, 18 Aug. 2009

25aTJ-10 Phonon anormaly in rare-earth hexaboride GdB_6
Igarashi R; Iwasa K; Saito K; Laulhe C; Kunii S; Nakao H; Murakami Y; Kuwahara K; Iga F; Sera M; Baron A; Tsutsui S
Meeting abstracts of the Physical Society of Japan, 18 Aug. 2009

29pTA-3 PrRu_4P_<12>の4f電子状態に対するRuサイトへのRh置換効果(29pTA スクッテルダイト,領域8(強相関系:高温超伝導,強相関f電子系など))
斉藤 耕太郎; Laulhe Claire; 岩佐 和晃; 村上 洋一
日本物理学会講演概要集, 03 Mar. 2009

29pTA-2 Electron hybridization effect on the crystal field excitation of Pr-filled skutterudite
Iwasa K.; Saito K.; Murakami Y.; Sugawara H.
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2009

28aTD-10 Multipolar ordering in the cubic RPd_3S_4 system (R: rare-earth metals)
Matsuoka E.; Usui D.; Watahiki M.; Sasaki Y.; Iwasa K.; Ohoyama K.; Nakamura S.; Nojima T.; Onodera H.
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2009

27aPS-5 4f electron state and superlattice structure of Pr(Ru_<1-x>Rh_x)_4P_<12>
Laulhe C.; Saito K.; Iwasa K.; Nakao H.; Murakami Y.
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2009

29pTD-9 Pressure effect on the spin states in RVO_3 (R=Y,Tb) studied by neutron scattering under high pressure
Bizen D; Nakao H; Iwasa K; Murakami Y; Osakabe T; Fujioka J; Yasue T; Miyasaka S; Tokura Y
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2009

20pQA-8 Phonon Anomalies and Electron-Lattice Interaction in Rare-Earth Compounds
Iwasa Kazuaki
Meeting abstracts of the Physical Society of Japan, 25 Aug. 2008

23aQA-6 PrOs_4P_<12>における結晶場準位の温度依存(23aQA スクッテルダイト化合物,領域8(強相関系:高温超伝導,強相関f電子系など))
斉藤 耕太郎; 岩佐 和晃; 村上 洋一; 菅原 仁
日本物理学会講演概要集, 25 Aug. 2008

21aQA-8 Mechanism of the Electric Polarization Flop in TbMnO_3
Sagayama H.; Abe N.; Arima T.; Iwasa K.
Meeting abstracts of the Physical Society of Japan, 25 Aug. 2008

20pQA-8 Phonon Anomalies and Electron-Lattice Interaction in Rare-Earth Compounds
Iwasa Kazuaki
Meeting abstracts of the Physical Society of Japan, 25 Aug. 2008

4f-electron multipole ordering and excitations in Pr-based filled skutterudites
岩佐 和晃; 桑原 慶太郎; 神木 正史
Solid state physics, Apr. 2008

23aYB-7 Magnetic control of the sign of electric polarization in RMnO_3
Abe N.; Taniguchi K.; Ohtani S.; Umetsu H.; Sagayama H.; Iwasa K.; Arima T.
Meeting abstracts of the Physical Society of Japan, 29 Feb. 2008

23aWR-6 Dynamical Jahn-Teller Effect due to p-f Mixing of Ce-monopnictides
Iwasa K.; Kohgi M.; Mignot J.-M.; Braden M.; Kitazawa H.
Meeting abstracts of the Physical Society of Japan, 29 Feb. 2008

24aWR-6 Inelastic neutron scattering study on PrFe_4Sb_<12> synthesized under high pressure
Kuwahara K.; Tanaka K.; Saito T.; Tatsuoka S.; Iwasa K.; Watanabe M.; Aoki Y.; Sato T.; Kohgi M.; Iwasa K.; Sugawara H.
Meeting abstracts of the Physical Society of Japan, 29 Feb. 2008

24aWR-2 Inelastic Neutron Scattering Study of Crystal Field Level in Pr(Ru_<1-x>Rh_x)_4P_<12>
Saito Kotaro; Hao Lijie; Iwasa Kazuaki; Murakami Youichi
Meeting abstracts of the Physical Society of Japan, 29 Feb. 2008

23pPSB-18 Quadrupolar ordering of PrPd_3S_4 III
Usui D.; Matsuoka E.; Iwasa K.; Ohoyama K.; Onodera H.
Meeting abstracts of the Physical Society of Japan, 29 Feb. 2008

Competition of Magnetic and Quadrupolar Order Parameters in HoB4
D. Okuyama; T. Matsumura; T. Mouri; N. Ishikawa; K. Ohoyama; H. Hiraka; H. Nakao; K. Iwasa; Y. Murakami
J. Phys. Soc. Jpn., 2008

Valence state in R4As3 (R = Yb and Eu) studied by resonant and non-resonant X-ray scattering
H. Nakao; K. Kiyoto; K. Nakatsuka; D. Bizen; T. Murata; S. Kodama; T. Matsumura; K. Iwasa; Y. Murakami; A. Ochiai
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS, Nov. 2007

24aXA-7 Crystalline Electric Field of YbAl_3C_3
Kato Yoshiaki; Nowatari Hiromi; Kosaka Masashi; Katano Susumu; Ohoyama Kenji; Suzuki Hiroyuki; Aso Naofumi; Iwasa Kazuaki
Meeting abstracts of the Physical Society of Japan, 21 Aug. 2007

21pPSB-17 Low-energy softening phonon of CeOs_4Sb_<12>
Iwasa K.; Itobe S.; Yang C.; Murakami Y.; Kohgi M.; Sugawara H.; Sato H.
Meeting abstracts of the Physical Society of Japan, 21 Aug. 2007

24pWG-4 Charge ordered state in Eu_3S_4 studied by a resonant x-ray scattering
Nakao H; Murata T; Bizen D; Shirane N; Matsumura T; Iwasa K; Murakami Y; Ochiai A
Meeting abstracts of the Physical Society of Japan, 21 Aug. 2007

Resonant X-ray scattering of PrRu4P12
K. Ishii; S. Tsutsui; L. Hao; T. Hasegawa; K. Iwasa; M. Tsubota; T. Inami; Y. Murakami; S. R. Saha; H. Sugawara; H. Sato
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, Mar. 2007

Orbital ordering and the dilute effect in copper fluoride
N. Tatami; Y. Ando; S. Niioka; H. Kira; M. Onodera; H. Nakao; K. Iwasa; Y. Murakami; T. Kakiuchi; Y. Wakabayashi; H. Sawa; S. Itoh
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, Mar. 2007

19aWP-9 Neutron diffraction study of Ce_<0.7>La_<0.3>B_6 in Phase IV
Kuwahara K.; Iwasa K.; Aso N.; Kohgi M.; Sera M.; Iga F.
Meeting abstracts of the Physical Society of Japan, 28 Feb. 2007

18aWP-5 Inelastic Neutron Scattering of YbAl_3C_3
Kato Yoshiaki; Nowatari Hiromi; Kosaka Masashi; Katano Susumu; Ohoyama Kenji; Suzuki Hiroyuki; Aso Naofumi; Iwasa Kazuaki
Meeting abstracts of the Physical Society of Japan, 28 Feb. 2007

21aWK-8 Magnetic Correlation in the Change from Semiconductor to Metal of CeOs_4Sb_<12> under Magnetic Field
Itobe S.; Iwasa K.; Yang C.P.; Kohgi M.; Kuwahara K.; Sugawara H.; Sato H.; Aso N.
Meeting abstracts of the Physical Society of Japan, 28 Feb. 2007

18aWP-3 Crystal Field Excitations in Quadrupolar Ordering Compounds YbX
Oyamada A.; Maegawa S.; Kuwahara K.; Kohgi M.; Ohoyama K.; Iwasa K.
Meeting abstracts of the Physical Society of Japan, 28 Feb. 2007

20aWP-4 Electron-Lattice Interaction Revealed from the Phonon Spectra of PrT_4Sb_<12>(T=Ru,Os)
Iwasa K.; Mori Y.; Hao L.; Murakami Y.; Kohgi M.; Sugawara H.; Sato H.
Meeting abstracts of the Physical Society of Japan, 28 Feb. 2007

20aWF-11 The observation of local structure near Zn^<2+> ion in KCu_xZn_<1-x>F_3
Tatami N; Ando Y; Niioka S; Kira H; Onodera M; Nakao H; Iwasa K; Murakami Y; Sawa H; Wakabayashi Y; Itoh S; Kakiuchi T
Meeting abstracts of the Physical Society of Japan, 28 Feb. 2007

20pWG-2 Magnetic phase transition of TbVO_3 observed under high pressure
Bizen D; Nakao H; Iwasa K; Murakami Y; Osakabe T; Miyasaka S; Tokura Y
Meeting abstracts of the Physical Society of Japan, 28 Feb. 2007

26aZR-3 NMR Studies on a mixing-type Quadrupolar Ordering in YbSb
Oyamada A.; Maegawa S.; Kuwahara K.; Kohgi M.; Ohoyama K.; Iwasa K.
Meeting abstracts of the Physical Society of Japan, 18 Aug. 2006

23pPSA-20 Single-crystal neutron diffraction on the pressure-induced insulating phase of PrFe_4P_<12>
Osakabe T.; Kawana D.; Kuwahara K.; Iwasa K.; Kikuchi D.; Aoki Y.; Kohgi M.; Sato H.
Meeting abstracts of the Physical Society of Japan, 18 Aug. 2006

25pXK-7 Magnetic excitation in geometrically frustrated HoB_4 studied by neutron inelastic scattering
Okuyama D.; Matsumura T.; Iwasa K.; Murakami Y.
Meeting abstracts of the Physical Society of Japan, 18 Aug. 2006

25aYA-12 Phonon anomaly of filled skutterudite compounds PrOs_4Sb_<12> and PrRu_4Sb_<12>
Mori Y.; Iwasa K.; Hao L.; Murakami Y.; Kohgi M.; Sugawara H.; Sato H.
Meeting abstracts of the Physical Society of Japan, 18 Aug. 2006

23pPSA-11 Magnetic Excitations in RFe_4P_<12> (R=Ce, Pr, Nd)
Iwasa K.; Hao L.; Mori Y.; Itobe S.; Sugawara H.; Kuwahara K.
Meeting abstracts of the Physical Society of Japan, 18 Aug. 2006

28pPSA-13 p-f hybridization effect appearing in the crystal-field excitations of Pr_<1-x>La_xRu_4P_<12>
Hasegawa T.; Hao L.; Iwasa K.; Horiuchi K.; Mori Y.; Kimura N.; Murakami N.
Meeting abstracts of the Physical Society of Japan, 04 Mar. 2006

30pUB-4 Resonant x-ray scattering of PrRu_4P_<12>
Ishii K.; Tsubota M.; Inami T.; Tsutsui S.; Hao L.; Hasegawa T.; Iwasa K.; Murakami Y.; Sugawara H.; Saha S.R.; Sato H.
Meeting abstracts of the Physical Society of Japan, 04 Mar. 2006

27pUA-5 f-Electron Orbital Ordering in Pr-Filled Skutterudites
Iwasa Kazuaki
Meeting abstracts of the Physical Society of Japan, 04 Mar. 2006

30aUF-8 Inelastic Neutron Scattering on Na_<0.35>CoO_2・nD_2O
Kubota M.; Oohara Y.; Ono K.; Matsumura T.; Iwasa K.; Sakurai Y.; Takada K.; Sasaki T.
Meeting abstracts of the Physical Society of Japan, 04 Mar. 2006

27pSC-4 Magnetic structure with long periodicity and coexistence of long-range and short-range magnetic order in geometrically frustrated HoB_4 studied by neutron scattering
Okuyama D.; Matsumura T.; Iwasa K.; Murakami Y.
Meeting abstracts of the Physical Society of Japan, 04 Mar. 2006

27aUE-1 Dilution effect
Ando Y; Tatami N; Niioka S; Murakami Y; Iwasa K; Nakao H; Kira H; Tamura H; Sawa H; Wakabayashi Y; Itoh S; Kakiuti T
Meeting abstracts of the Physical Society of Japan, 04 Mar. 2006

Charge ordered state in Yb4As3 studied by a resonant X-ray scattering technique
H. Nakao; K. Kiyoto; S. Kodama; D. Bizen; T. Matsumura; K. Iwasa; Y. Murakami; A. Ochiai
LOW TEMPERATURE PHYSICS, PTS A AND B, 2006

22aYG-8 X-ray diffraction under high pressure and low temperature on the ordered states of PrFe_4P_<12>
Kawana D.; Sagayama H.; Sato M.; Kuwahara K.; AOki Y.; Kohgi M.; Sato H.; Iwasa K.; Sugawara H.
Meeting abstracts of the Physical Society of Japan, 19 Aug. 2005

Magnetic excitation in the heavy electron state of Pr_<0.85>La_<0.15>Fe_4P_<12>
Hao L.; Hasegawa T.; Horiuchi K.; Iwasa K.; Murakami Y.; Kuwahara K.; Kohgi M.; Sugawara H.; Aoki Y.; Sato H.
Meeting abstracts of the Physical Society of Japan, 19 Aug. 2005

19aYG-5 Direct Observation of Quadrupolar Excitons in the Heavy-Fermion Superconductor PrOs_4Sb_<12>
Kuwabara K.; Iwasa K.; Kohgi M.; Kaneko K.; Medoki N.; Raymond S.; Measson M. -A.; Flouquet J.; Sugawara H.; Aoki Y.; Sato H.
Meeting abstracts of the Physical Society of Japan, 19 Aug. 2005

22pYG-1 Neutron diffraction study of antiferromagnetic phase transition of CeOs_4Sb_<12>
Iwasa K.; Yang C. P.; Kohgi M.; Sugawara H.; Sato H.; Aso N.
Meeting abstracts of the Physical Society of Japan, 19 Aug. 2005

19pXD-4 Valence fluctuated state in Yb_4As_3 studied by a resonant x-ray scattering technique
Nakao H; Kiyoto K; Bizen D; Kodama S; Matsumura T; Iwasa K; Murakami Y; Ochiai A
Meeting abstracts of the Physical Society of Japan, 19 Aug. 2005

Neutron scattering studies of order parameters and excitations in antiferro-quadrupolar phase of PrFe₄P₁₂
Hao, L.; Iwasa, K.; Kuwahara, K.; Kohgi, M.; Sugawara, H.; Aoki, Y.; Sato, H.; Matsuda, T.D.; Mignot, J.-M.; Gukasov, A.; Nishi, M.
Physica B: Condensed Matter, 30 Apr. 2005

Anomalous thermal expansion in the metallic phase of SmS under high pressure
K Iwasa; T Tokuyama; M Kohgi; NK Sato; N Mori
PHYSICA B-CONDENSED MATTER, Apr. 2005, [Reviewed]

27aWA-12 Magnetic form factor of URu_2Si_2
Kuwahara K.; Kohgi M.; Iwasa K.; Nishi M.; Nakajima K.; Yokoyama J.; Amitsuka H.
Meeting abstracts of the Physical Society of Japan, 04 Mar. 2005

25pTA-12 Polarized-neutron diffraction study of superlattice due to crystal-field state and atomic displacements in PrRu_4P_<12>
Iwasa K.; Hao L.; Hasegawa T.; Horiuchi K.; Takagi T.; Mori Y.; Murakami Y.
Meeting abstracts of the Physical Society of Japan, 04 Mar. 2005

25aPS-55 Ce_3Ir_4Sn_<13>の磁気構造と結晶場の研究(領域8ポスターセッション(f電子系等),領域8(強相関系:高温超伝導,強相関f電子系など))
名越 千代子; Changping Yang.; 神木 正史; 青木 勇二; 真田 翔太朗; 菅原 仁; 佐藤 英行; 長壁 豊隆; 目時 直人; 本多 史憲; 金子 耕士; Jnen Shintar; 伊藤 晋一; 大山 研司; 岩佐 和晃
日本物理学会講演概要集, 04 Mar. 2005

25aPS-28 Pressure effect on lattice anomaly of PrFe_4P_<12>
Kawana D.; Sagayama H.; Sato M.; Kuwahara K.; Aoki Y.; Kohgi M.; Sato H.; Iwasa K.; Sugawara H.; Wakabayashi Y.; Sawa H.
Meeting abstracts of the Physical Society of Japan, 04 Mar. 2005

22aYG-13 Synchrotron Radiation X-ray Diffraction Study of M-I Transition in PrRu_4P_<12> under High Pressure
Sagayama H.; Wakabayashi Y.; Sawa H.; Kawana D.; Kuwahara K.; Kohgi M.; AOki Y.; Sato H.; Sugawara H.; Iwasa K.
Meeting abstracts of the Physical Society of Japan, 2005

12aPS-90 Magnetic and Lattice Modulation Structure of Eu_3Ir_4Sn_<13> and Gd_3Ir_4Sn_<13>
Nagoshi C; Yamamoto Y; Kuwahara K; Iwasa K; Kohgi M; Yokoo T; Arai M; Sugawara H; Aoki Y; Sato H
Meeting abstracts of the Physical Society of Japan, 25 Aug. 2004

12aRA-2 Neutron scattering study on low energy excitations of PrOs_4Sb_<12>
Kuwahara K.; Iwasa K.; Kohgi M.; Kaneko K.; Metoki N.; Sugawara H; Aoki Y.; Sato H.; Raymond S.; Flouquet J.
Meeting abstracts of the Physical Society of Japan, 25 Aug. 2004

14pPSA-62 4f-electron States of PrRu_4P_<12> Studied by Neutron Scattering
Hao Lijie; Hasegawa T; Takagi T; Iwasa K; Kuwahara K; Kohgi M; Saha S R; Sugawara H; Aoki Y; Sato H
Meeting abstracts of the Physical Society of Japan, 25 Aug. 2004

14pPSA-67 Neutron scattering from CeOs_4Sb_b_<12>
Yang C P; Kohgi M; Iwasa K; Kuwahara K; Sugawara H; Sato H
Meeting abstracts of the Physical Society of Japan, 25 Aug. 2004

14pPSA-53 Anomalous Lattice Vibration in PrOs_4Sb_<12>
Iwasa K; Kohgi M; Sugawara H; Sato H
Meeting abstracts of the Physical Society of Japan, 25 Aug. 2004

12aRC-7 Investigation of phase of AFQ and AFM orders in TbB_2C_2 by resonant x-ray scattering in magnetic fields
Okuyama D; Matsumura T; Nakao H; Iwasa K; Murakami Y; Onodera H; Tobo A; Wakabayashi Y; Sawa H
Meeting abstracts of the Physical Society of Japan, 25 Aug. 2004

14aRC-5 Charge Ordered State in Yb_4As_3 studied by Resonant X-ray Scattering
Kiyoto K; Kodama S; Bizen D; Nakao H; Matsumura T; Iwasa K; Murakami Y; Ochiai A
Meeting abstracts of the Physical Society of Japan, 25 Aug. 2004

27aXD-12 Coexistence of SDW and CDW in the Kondo-lattice compound Ce(Ru_<1-x>Rh_x)_2Si_2 II
Tabata Y.; Taniguchi T.; Kawarazaki S.; Narumi Y.; Tanaka Y.; Katsumata K.; Staub U.; Ishikawa T.; Kohgi M.; Iwasa K.
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2004

28pPSA-65 Single Crystal Growth and Magnetic Properties of UCu_2Si_2
Matsuda T D; Haga Y; Galatanu Andrei; Ikeda S; Yamanoto E; Ito M; Shishido H; Yamada M; Yamaura J; Hedo M; Uwatoko Y; Matsumoto T; Sugimoto T; Tada T; Noguchi S; Kuwahara K; Iwasa K; Kohgi M; Settai R; Onuki Y
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2004

30aXE-1 Inelastic neutron scattering study on PrOs_4Sb_<12>
Kuwahara K; Iwasa K; Kohgi M; Kaneko K; Metoki N; Sugawara H; Aoki Y; Sato H; Raymond S; Flouguet J.
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2004

28aPS-90 Observation of Orbital Ordering in YVO_3
Togasaki M; Ichikawa H; Kousaka Y; Souma S; Takeda M; Matsumura T; Iwasa K; Akimitsu J
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2004

28aPS-1 Orbital Ordering of Ca_<1.8>Sr_<0.2>RuO_4 after Metamagnetic Transition
Soma S.; Kousaka Y; Ichikawa H.; Akimitsu J.; Matsumura T.; Iwasa K; Nishi M.; Nakatsuji S.; Maeno Y.
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2004

30pXE-3 Natron scattering studies on antiferro-quadrupolar ordering and magnetic excitation of PrFe_4P_<12>
Iwasa K; Hao L; Kuwahara K; Kohgi M; Sugawara H; Aoki Y; Sato H; Matsuda T D; Mignot J-M; Gukasov A; Nishi M
Meeting abstracts of the Physical Society of Japan, 03 Mar. 2004

Coexistence of SDW and CDW in the Kondo-lattice compound Ce(Ru_<1-x>Rh_x)_2Si_2
Tabata Y.; Taniguchi T.; Kawarazaki S.; Narumi Y.; Tanaka Y.; Katsumata K.; Kimura S.; Ishikawa T.; Yabashi M.; Kohgi M.; Iwasa K.
Meeting abstracts of the Physical Society of Japan, 15 Aug. 2003

Novel change of 4f-electron states on the metal-insulator transition of PrRu_4P_<12> observed by inelastic neutron scattering
Iwasa K.; Hao Li jie; Kuwahara K.; Kohgi M.; Saha S. R.; Sugawara H.; Aoki Y.; Sato H.
Meeting abstracts of the Physical Society of Japan, 15 Aug. 2003

Inelastic neutron scattering study on PrOs_4Sb_<12>
Kuwahara K.; Iwasa K.; Kohgi M.; Kaneko K.; Araki S.; Metoki N.; Sugawara H.; Aoki Y.; Sato H.; Raymond S.; Flouquet J.
Meeting abstracts of the Physical Society of Japan, 15 Aug. 2003

Single Crystal Growth and Magnetic Properties of New ternary Uranium Compound
Matsuda T. D; Haga Y; Galatanu Andrei; Ikeda S; Shishido H; Yamada M; Kuwahara K; Iwasa K; Kohgi M; Ito M; Yamamoto E; Settai R; Onuki Y
Meeting abstracts of the Physical Society of Japan, 15 Aug. 2003

Resonant x-ray scattering study on the anomalous ordered phase of PrFe_4P_<12>
Ishii K; Inami T; Murakami Y; Hao Li jie; Iwasa K; Kohgi M; Aoki Y; Sugawara H; Sato H; Imada S; Nakao H; Wakabayashi Y; Sawa H
Meeting abstracts of the Physical Society of Japan, 15 Aug. 2003

Magnetic structure and lattice distortion of GdB_6
Yamamoto R; Kuwahara K; Iwasa K; Kohgi M; Nakao H; Ishii K; Murakami Y; Kunii A
Meeting abstracts of the Physical Society of Japan, 15 Aug. 2003

Crystal-Lattice Modulation of the Metal-Insulator Transition System PrRu4P12 Studied by X-Ray Diffraction
Hao Lijie; Iwasa K.; Kuwahara K.; Kohgi M.; Saha S. R.; Sugawara H.; Aoki Y.; Sato H.; Sekine C.; Lee C. H.; Harima H.
Meeting abstracts of the Physical Society of Japan, 06 Mar. 2003

Temperature dependence of lattice parameters and successive sturctural phase transition in CeRhAs
Nakajima Motoki; Iwasa Kazuaki; Kohgi Masafumi; Masumori Kenta; Sasakawa Tetsuya; Takabatake Toshiro
Meeting abstracts of the Physical Society of Japan, 06 Mar. 2003

Magnetic P-T phase diagrams of Ce-monopnictides
Osakabe T.; Kawana D.; Kohgi M.; Iwasa K.; Kitazawa H.; Haga Y.
Meeting abstracts of the Physical Society of Japan, 06 Mar. 2003

Magnetic Phase Diagram under High Pressure on CeP
Kawana D.; Osakabe T.; Hannan A.; Kuwahara K.; Iwasa K.; Kohgi M.
Meeting abstracts of the Physical Society of Japan, 06 Mar. 2003

Neutron diffraction study of field-induced antiferro-quadrupolar ordering of PrOs_4Sb_<12>
Iwasa K.; Nakajima M.; Kohgi M.; Araki S.; Kaneko K.; Metoki N.; Mignot J. M.; Gukasov A.; Bernhoeft N.; Sugawara H.; Osaki S.; Aoki Y.; Sato H.
Meeting abstracts of the Physical Society of Japan, 06 Mar. 2003

中性子およびX線散乱実験によるスクッテルダイト化合物の研究(スクッテルダイト化合物研究の現状と展望,研究報告)
神木 正史; 岩佐 和晃; 桑原 慶太郎
物性研究, 2003

EXCED - epithermal neutron diffractometer at KENS
K Kuwahara; S Sugiyama; K Iwasa; M Kohgi; M Nakamura; Y Inamura; M Arai; S Kunii
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, Dec. 2002

Successive structural phase transitions and energy-gap formation in CeRhAs.
Nakajima Motoki; Iwasa Kazuaki; Kohgi Masahumi; Sasakawa Tetsuya; Takabatake Toshiro
Meeting abstracts of the Physical Society of Japan, 13 Aug. 2002

High pressure X-ray diffraction study of URu2Si2
Kuwahara K; Sagayama H; Iwasa K; Kohgi M; Miyazaki S; Nozaki J; Nogami J; Yokoyama M; Amitsuka H; Nakao H; Murakami Y
Meeting abstracts of the Physical Society of Japan, 13 Aug. 2002

Anomalous thermal expansion on the pressure-induced insulator-metal transition of SmS
Iwasa K; Tokuyama T; Kohgi M; Sato N.K; Mori N
Meeting abstracts of the Physical Society of Japan, 13 Aug. 2002

Field-induced magnetization and excited states on the transition between heavy-electron state and quadrupolar-ordering state of PrFe4P12
Iwasa K; Hao L; Nakajima M; Kohgi M; Sugawara H; Aoki Y; Matsuda T.D; Sato H
Meeting abstracts of the Physical Society of Japan, 13 Aug. 2002

26pXJ-11 Magnetic field direction dependence of spin exciattions in the S=1/2 one-dimensional antiferromagnet Yb_4As_3
Kohgi M.; Iwasa K.; Mignot J.-M.; Hiess A.; Aoki H.; Ochiai A.
Meeting abstracts of the Physical Society of Japan, 01 Mar. 2002

24aPS-23 Neutron scattering studies of the low-temperature phases of Ce_<0.75>La_<0.25>lB_6
Iwasa K.; Kuwahara K.; Kohgi M.; Fischer P.; Donni A.; Hansen T.; Kunii S.
Meeting abstracts of the Physical Society of Japan, 01 Mar. 2002

24aPS-49 Magnetic Phase Diagram of CeP Under High Pressure
Hannan A.; Osakabe T.; Iwasa K.; Kohgi M.
Meeting abstracts of the Physical Society of Japan, 01 Mar. 2002

25pWB-5 Structural transition and antiferro-Quadrupolar ordering in the anomalous low-temperature phase of PrFe_4p_<12>
Hao L; Iwasa K; Kawana D; Watanabe Y; Kuwahara K; Kohgi M; Sugawara H; Aoki Y; Matsuda T.D; Sato H
Meeting abstracts of the Physical Society of Japan, 01 Mar. 2002

Magnetic form factor of UGe2 under high pressure
K. Kuwahara; H. Sagayama; K. Iwasa; M. Kohgi; Y. Haga; Y. Onuki; K. Kakurai; M. Nishi; K. Nakajima; N. Aso; Y. Uwatoko
Physica B: Condensed Matter, 2002

Critical scattering from the percolating magnet, RbMn_<0.31>Mg_<0.69>F_3
Itoh Shinichi; Iwasa Kazuaki; Bull M. J.
Meeting abstracts of the Physical Society of Japan, 03 Sep. 2001

Magnetic Structure of Eu_3Ir_4Sn_<13> with Orthogonal One-Dimensional Chains of Eu_<2+> Studied by Neutron Scattering.
名越 千代子; 岩佐 和晃; 桑原 慶太郎; 神木 正史; 菅原 仁; 青木 勇二; 佐藤 英行; 大山 研司
Meeting abstracts of the Physical Society of Japan, 03 Sep. 2001

X-ray diffraction study of crystal-lattice modulation accompanied with electrical-resistivity anomaly of CeRhAs.
Nakajima Motoki; Iwasa Kazuaki; Kohgi Masafumi; Suemitsu Toshiaki; Takabatake Toshiro
Meeting abstracts of the Physical Society of Japan, 03 Sep. 2001

Magnetic structure and lattice distortion of GdB_6 studied by epithermal neutron diffraction
Kuwahara K.; Sugiyama S.; Iwasa K.; Kohgi M.; Nakamura M.; Inamura Y.; Arai M.; Kunii S.
Meeting abstracts of the Physical Society of Japan, 03 Sep. 2001

Yb4As3における電荷秩序形成と磁性--交替磁場効果による一次元磁性の新しい現象 (「極端条件下における中性子回折・散乱」第3回ワークショップ報告書)
岩佐 和晃; 神木 正史; Mignot J.M.
KURRI-KR, 13 Mar. 2001

Magnetic Form Factor in UGe_2 under High Pressure
Sagayama H.; Kuwahara K.; Iwasa K.; Kohgi M.; Haga Y.; Onuki Y.; Kakurai K.; Nishi M.; Nakajima K.; Aso N.; Uwatoko Y.
Meeting abstracts of the Physical Society of Japan, 09 Mar. 2001

Phonon anomaly appearing only in the magnetic ordered phases of CeSb
Iwasa K.; Kohgi M.; Braden M.; Mignol J. -M.; Kitazawa H.
Meeting abstracts of the Physical Society of Japan, 09 Mar. 2001

Structural phase transition in anomalous low-temperature phase of filled skutterudite PrFe_4P_<12>
Iwasa K; Watanabe Y; Kuwahara K; Kohgi M; Sugwara H; Aoki Y; Matsuda D; Sato H
Meeting abstracts of the Physical Society of Japan, 09 Mar. 2001

Magnetic Form Factor in UGe2　　　　　　　　　　　　　　　
Hajime Sagayama; Keitaro Kuwahara; Kazuaki Iwasa; Masafumi Kohgi; Yoshinori Haga; Yoshichika Onuki; Kazuhisa Kakurai; Masakazu Nishi; Kenji Nakajima; Naofumi Aso
Journal of the Physical Society of Japan, 2001

Neutron-scattering study of magnetic-field effect on ID quantum spin dynamics of Yb_4As_3
Iwasa K.; Kohgi M.; Mignot J. M.; Gukasov A.; Fak B.; Shibata N.; Ochiai A.; Aoki H.; Suzuki T.
Meeting abstracts of the Physical Society of Japan, 10 Sep. 2000

22aTB-8 Direct Observation of 4f-electron Orbital Order in CeSb by X-ray Diffraction
Hannan A.; Iwasa K.; Kohgi M.; Suzuki T.
Meeting abstracts of the Physical Society of Japan, 10 Sep. 2000

Measurement of the orbital ordering of 4f-electron under high pressure and low temperature in CeP
Shobu T.; Noda Y.; Iwasa K.; Hannan A.; Kohgi M.
Meeting abstracts of the Physical Society of Japan, 10 Sep. 2000

Lattice Moduration with Magnetic Ordering at High Pressure and Low Tempreture in CeP II
Shobu T.; Noda Y.; Iwasa K.; Hannan A.; Kohgi M
Meeting abstracts of the Physical Society of Japan, 10 Mar. 2000

Anisotropic field-induced magnetic moments in the charge-ordered phase of Yb_4As_3
Iwasa K.; Kohgi M.; Ochiai A.; Aoki H.; Gukasaov A.; Mignot J. -M.; Suzuki T.
Meeting abstracts of the Physical Society of Japan, 10 Mar. 2000

MAGNETIC FORM FACTOR AND MAGNETIC EXCITATIONS OF THE HEAVY ELECTRON SYSTEM UGe_2
Sagayama H.; Kuwahara K.; Iwasa K.; Kohgi M.; Haga Y.; Onuki Y.; Kakurai K.; Nishi M.; Nakajima K.
Meeting abstracts of the Physical Society of Japan, 10 Mar. 2000

24aH-3 Lattice Moduration with Magnetic Ordering at High Pressure and Low Tempreture in CeP
Shobu t; Noda Y; Iwasa K; Kohgi M
Meeting abstracts of the Physical Society of Japan, 03 Sep. 1999

24aH-6 Crystal Lattice Anomaly of CeSb Under High Pressure
Hannan A; Iwasa K; Kohgi M; Suzuki T
Meeting abstracts of the Physical Society of Japan, 03 Sep. 1999

26pS-4 Spin-correlation functions in 2D percolating Ising antiferromagnets due to random-field effect
Iwasa K; Ikeda H
Meeting abstracts of the Physical Society of Japan, 03 Sep. 1999

25pYQ-11 Critical dynamics in 2-d lsing diluted antiferromagnet, Rb_2Co_xMg_<1-x>F_4
kouchi Y; Itoh S; Iwasa K; Ikeda S; Ikeda H
Meeting abstracts of the Physical Society of Japan, 03 Sep. 1999

24pH-7 Gap formation in the one-dimensional spin exciattions in Yb_4As_3 under magnetic field
Kohgi M; Iwasa K; Mignot J.M.; Fak B; Ochiai A; Aoki H
Meeting abstracts of the Physical Society of Japan, 03 Sep. 1999

25pPSA-55 Phase transition forming a long-period crystal-lattice modulation in Eu_3Ir_4Sn_<13>
Iwasa K; Maeda F; Kohgi M; Sato H; Aoki Y; Sugawara H
Meeting abstracts of the Physical Society of Japan, 03 Sep. 1999

31p-D-5 Crystal-lattice modulation in the magnetic ordered phases of the low-carriar system CeSb
Arakaki Y.; Kohgi M.; Iwasa K.; Suzuki T.
Meeting abstracts of the Physical Society of Japan, 15 Mar. 1999

31p-D-11 Magnetic moments in charge ordered state of Yb_4As_3 studied by polarized neutron scattering
Iwasa K.; Kohgi M.; Ochiai A.; Aoki H.; Gukasov A.; Mignot J.M.
Meeting abstracts of the Physical Society of Japan, 15 Mar. 1999

Polarized-neutron study of the magnetic-polaron state in CeP
Iwasa, K.; Kohgi, M.; Haga, Y.; Suzuki, T.; Kakurai, K.; Nishi, M.; Nakajima, K.; Link, P.; Gukasov, A.; Mignot, J.-M.
Physica B: Condensed Matter, 1999

Polarized neutron scattering study on 4f-electron wave function of magnetic state in CeP
IWASA K.; KOHGI M.; HAGA Y.; SUZUKI T.; KAKURAI K.; NISHI M.; NAKAJIMA K.; LINK P.; GUKASOV A.; MIGNOT J.-M.
Meeting abstracts of the Physical Society of Japan, 05 Sep. 1998

Magnetic structures of the low-carrier system CeAs under high pressure
OSAKBE T.; KOHGI M.; IWASA K.; KUBOTA M.; YOSHIZAWA H.; HAGA Y.; SUZUKI T.
Meeting abstracts of the Physical Society of Japan, 05 Sep. 1998

X-ray of super lattice structures in the magnetic ordcred phases of CeSb
ARAKAKI Y.; KOHGI M.; IWASA K.; SUZUKI T.
Meeting abstracts of the Physical Society of Japan, 05 Sep. 1998

Anisotropic Spontaneous Magneto-striction of UGe_2
INAMURA T.; KOHGI M.; IWASA K.; HAGA Y.; ONUKI Y.
Meeting abstracts of the Physical Society of Japan, 05 Sep. 1998

Crystal lattice anomaly of Ce_<0.75>La_<0.25>B_6 observed in neutron scattering
IWASA K.; KOHGI M.; SUZUKI O.; GOTO T.; METOKI N.; KOIKE Y.; KUNII S.
Meeting abstracts of the Physical Society of Japan, 05 Sep. 1998

Physcial Properties of U_3Pd_<20>Si_6 I
TATEIWA N.; KIMURA N.; AOKI H.; METOKI N.; IWASA K.; KOHGI K.; NEMOTO Y.; GOTO T.; KOMATSUBARA T.
Meeting abstracts of the Physical Society of Japan, 05 Sep. 1998

Physcial Properties of U_3Pd_<20>Si_6 II
TATEIWA N.; KIMURA N.; AOKI H.; METOKI N.; IWASA K.; KOHGI K.; NEMOTO Y.; GOTO T.; KOMATSUBARA T.
Meeting abstracts of the Physical Society of Japan, 05 Sep. 1998

Magnetic from factor of a low-carrier-density system CeP(II)
IWASA K.; KOHGI M.; HAGA Y.; SUZUKI T.; KAKURAI K.; NISHI M.; NAKAJIMA K.; LINK P.; GUKASOV A.; MIGNOT J.-M.
Meeting abstracts of the Physical Society of Japan, 10 Mar. 1998

X-ray diffraction study of CeB_6 in a magnetic field
ICHIKAWA H.; EGUCHI N.; MIYANO T.; AKIMITSU J.; OHSUMI H.; SHIMOMURA S.; TAJIMA K.; IWASE K.; KOHGI M.; SERA M.; KUNII S.
Meeting abstracts of the Physical Society of Japan, 10 Mar. 1998

Magnetoelastic properties of CeP
T. Takeuchi; Y. Haga; K. Iwasa; M. Kohgi; T. Suzuki
Journal of Magnetism and Magnetic Materials, 1998

6a-PS-61 Low-temperature X-ray diffraction study of RB_6(R=Ce and Gd)
Iwasa K.; Nakajima N.; Kohgi M.; Kunii S.
Meeting abstracts of the Physical Society of Japan, 16 Sep. 1997

5a-YF-11 Magnetic form factor of a low-carrier-density system CeP
Iwasa K.; Kohgi M.; Haga Y.; Suzuki T.; Kakurai K.; Nishi M.; Nakajima K.
Meeting abstracts of the Physical Society of Japan, 16 Sep. 1997

28p-PSB-34 X-ray diffraction study of low-carrier systems CeX(X=P, As)and Yb_4As_3
Iwasa K.; Kohgi M.; Nakajima N.; Hisazaki Y.; Yoshitake R.; Tajima K.; Wakabayashi N.; Haga Y.; Ochiai A.; Suzuki T.
Meeting abstracts of the Physical Society of Japan, 17 Mar. 1997

29a-P-2 Elastic anomalies and CEF effect of CeP and CeAs
Morita K.; Nakamura S.; Goto T.; Iwasa K.; Kohgi M.; Uesawa A.; Suzuki T.
Meeting abstracts of the Physical Society of Japan, 17 Mar. 1997

Charge order and one-dimensional properties of Yb₄As₃
Kohgi, M.; Iwasa, K.; Ochiai, A.; Suzuki, T.; Mignot, J.-M.; Gillon, B.; Gukasov, A.; Schweizer, J.; Kakurai, K.; Nishi, M.; D{\"o}nni, A.; Osakabe, T.
Physica B: Condensed Matter, 1997

Thermal expansion of low-carrier systems Ce_xLa_<1-x>P and Yb_4As_3
Iwasa K.; Kohgi M.; Nakajima N.; Osumi H.; Tajima K.; Wakabayashi N.; Haga Y.; Ochiai A.; Suzuki T.
Abstracts of the meeting of the Physical Society of Japan. Sectional meeting, 13 Sep. 1996

Magnetic Phase Diagram of the Low Carrier System CeP
Osakabe T.; Kohgi M.; Iwasa K.; Nakajima N.; Haga Y.; Suzuki T.
Abstracts of the meeting of the Physical Society of Japan. Sectional meeting, 13 Sep. 1996

1a-pS-11 X ray diffraction from low carrier rare earth compounds under low temperature and magnetic fields
Iwasa K.; Kohgi M.; Nakajima N.; Kidokoro M.; Osumi H.; Tajima K.; Ochiai A.; Haga Y.; Suzuki T.
Abstracts of the meeting of the Physical Society of Japan. Annual meeting, 15 Mar. 1996

3P-YF-5 MAGNETIC STRUCTURE AND MAGNETIC EXCITATION OF THE LOW CARRIER SYSTEM CeP
Osakabe T.; Kohgi M.; Iwasa I; Okayama Y.; Haga K. Y.; Suzuki T.
Abstracts of the meeting of the Physical Society of Japan. Annual meeting, 15 Mar. 1996

3P-YF-1 Charge order and one-dimensional properties of Yb_4As_3
Kohgi M.; Iwasa K.; Mignot J.-M.; Gillon B.; Goukassov A.; Ochiai A.; Suzuki T.; Kakurai K.; Nishi M.; Osakabe T.
Abstracts of the meeting of the Physical Society of Japan. Annual meeting, 15 Mar. 1996

MAGNETIC STRUCTURE OF THE LOW CARRIER SYSTEM CeP UNDER HIGH PRESSURE
Osakabe T.; Kohgi M.; Okayama Y.; Iwasa K.; Haga Y.; Suzuki T.
Abstracts of the meeting of the Physical Society of Japan. Sectional meeting, 12 Sep. 1995

3a-YA-13 Spin dynamics in a percolating Ising magnet
Ikeda H; Iwasa K; Andersen K.H; Eccleston R.S
Abstracts of the meeting of the Physical Society of Japan. Sectional meeting, 16 Aug. 1994

30p-PSA-2 Localized Magnon in Two-demensional Mixed Antiferromagnets
Iwasa K; Ikeda H; Andersen K.H.
Abstracts of the meeting of the Physical Society of Japan. Annual meeting, 16 Mar. 1994

14a-R-7 Fracton excitations in a diluted Heisenberg antiferromagnet near the percolation threshold : RbMn_<0.39>Mg_<0.61>F_3
Ikeda H.; Fernandez-Baca J.A.; Nicklow R.M.; Takahashi M.; Iwasa K.
Abstracts of the meeting of the Physical Society of Japan. Sectional meeting, 20 Sep. 1993

14a-R-9 High energy resolution inelastic neutron scattering of RbMn_cMg_<1-c>F_3 (c=0.5) under magnetic field
Iwasa K.; Ikeda H.; Andersen Ken Holst; Takahashi M.
Abstracts of the meeting of the Physical Society of Japan. Sectional meeting, 20 Sep. 1993

14a-R-6 Self-similarity of the magnetic order in two-dimensional percolating antiferromagnets
Ikeda H.; Iwasa K.; Andersen K.H.
Abstracts of the meeting of the Physical Society of Japan. Sectional meeting, 20 Sep. 1993

1a-PS-55 Neutron diffraction of magnetic layered compounds under high pressure
Iwasa K.; Nishi M.; Suzuki J.; Ikeda H.
Abstracts of the meeting of the Physical Society of Japan. Annual meeting, 16 Mar. 1993

1p-C-4 INLASTIC PULSE NEUTRON SCATTERING ON κ-(BEDT-TTF)_2Cu(NCS)_2
Shimazu T.; Sasaki T.; Toyota N.; Shibata K.; Kajitani T.; Lang M.; Sugimoto D.; Iwasa K.; Ikeda S.
Abstracts of the meeting of the Physical Society of Japan. Annual meeting, 16 Mar. 1993

28a-N-9 Devil's Staircase of Magnetic Layered Compound under High pressure
NISHI Masakazu; IWASA Kazuaki; SUZUKI Jyunichi; IKEDA Hironobu
秋の分科会講演予稿集, 14 Sep. 1992

30p-PS-23 Lattice modulations induced by magnetoelastic effect in crystals in containing rare earth elements
Iwasa K; Wakabayashi N; Shigeoka T; Takabatake T; Fujii H
年会講演予稿集, 12 Mar. 1992

27a-F-14 Lattice modulation of Tm crystal by magnetoelastic effect
Iwasa K.; Wakabayashi N.
春の分科会講演予稿集, 11 Mar. 1991

日本大百科全書（ニッポニカ）
Contributor
小学館, Dec. 2014

〔Major achievements〕Ce3T4Sn13 (T = Co, Rh, Ir)のカイラル相における4f電子状態とWeyl-Kondo半金属　　　　　　　　　　　　　　　
岩佐和晃; 河村聖子; 村井直樹; 中島健次; J.-M. Mignot; S. Raymond; Paul Steffens; 松田達磨; 青木勇二; 川崎郁斗; 藤森伸一; 山上浩志; 横山淳; D. T. Adroja; and A. M. Strydom
日本物理学会第78回年次大会, Sep. 2023
202309, 202609

〔Major achievements〕Remeika相物質Eu3T4Sn13(T = Rh and Ir)のカイラル結晶構造と磁気秩序　　　　　　　　　　　　　　　
熊田隆伸; 鈴木陽太郎; 下田愛海; 今関啓雅; 黒澤航海; 岩佐和晃; 桑原慶太郎; 大山研司; 星川晃範; 石垣徹; 佐賀山基; 奥山大輔; 中尾裕則; 石角元志
日本物理学会第78回年次大会, Sep. 2023
202309, 202609

〔Major achievements〕Znイオン置換したCeCoIn5の超伝導と反強磁性秩序の共存　　　　　　　　　　　　　　　
井能楓; 小日向実佳; 細貝明日香; 岩佐和晃; 大山研司; 松尾晶; 金道浩一; 天谷健一; 横山淳
日本物理学会第78回年次大会, Sep. 2023
202309, 202609

Quantum beam scattering studies on magnetic ordering and structural phase transitions in Tb3Co4Sn13
Y. Suzuki; K. Iwasa; T. Kumada; W. Kurosawa; Y. Uramoto; K. Suzumura; K. Tsuge; K. Kuwahara (Ibaraki University); H. Sagayama; D. Okuyama; H. Nakao (KEK); M. Ishikado (CROSS); K. Ohoyama (Ibaraki University)
International Symposium of Quantum Beam Science at Ibaraki University 2023 (ISQBS2023), Nov. 2023, 茨城大学大学院理工学研究科量子線科学専攻
202411, 202411

Crystal structural phase transition and magnetic properties of Pr3Co4Sn13
K. Tsuge (Faculty of Science; Ibaraki Univ.); K. Iwasa (Frontier Research center; Ibaraki Univ.); T. Kumada; W. Kurosawa; Y. Suzuki (Graduate School of Sci. and Eng.; Ibaraki Univ.); Y. Uramoto; K. Suzumura (Faculty of Science; Ibaraki Univ.); K.Kuwahara (Graduate School of Sci. and Eng.; Ibaraki Univ.); H. Sagayama; D. Okuyama (KEK IMSS); M. Ishikado (CROSS)
International Symposium of Quantum Beam Science at Ibaraki University 2023 (ISQBS2023), Nov. 2023, 茨城大学大学院理工学研究科量子線科学専攻
202411, 202411

X-ray and neutron diffraction experiments for Gd3Co4Sn13
K. Suzumura (Faculty of Sci.; Ibaraki Univ.); K. Iwasa (Frontier Research Center of Ibaraki; Univ.); T. Kumada; W. Kurosawa; Y. Suzuki (Graduate School of Sci. and Eng.; Ibaraki Univ); Y. Uramoto; K. Tsuge (Faculty of Sci.; Ibaraki Univ.); K.Kuwahara; K. Ohoyama (Graduate School of Sci. and Eng.; Ibaraki Univ); H. Sagayama; D. Okuyama(IMSS KEK); M. Ishikado (CROSS)
International Symposium of Quantum Beam Science at Ibaraki University 2023 (ISQBS2023), Nov. 2023, 茨城大学大学院理工学研究科量子線科学専攻
202411, 202411

Crystal Structures and Magnetic Orderings in the Remeika Phase Compounds Eu3T4Sn13 (T = Rh and Ir)
T. Kumada; Y. Suzuki; A. Shimoda; H. Imazeki; W. Kurosawa; K. Iwasa; K. Kuwahara; K. Ohoyama; A. Hoshikawa (Ibaraki University); H. Sagayama; D. Okuyama; H. Nakao (IMSS KEK); M. Ishikado; T. Ishigaki (CROSS)
International Symposium of Quantum Beam Science at Ibaraki University 2023 (ISQBS2023), Nov. 2023, 茨城大学大学院理工学研究科量子線科学専攻
202411, 202411

Possibility of magnetic frustration of the Nd-based Remeika phase compounds
W. Kurosawa; K. Iwasa; T. Kumada; Y. Suzuki; Y. Uramoto; K. Suzumura; K. Tsuge; A. Shimoda; H. Imazeki; K. Kuwahara (Ibaraki Univ); H. Sagayama; D. Okuyama; H. Nakao (IMSS KEK); M. Ishikado (CROSS); S. Asai; T. Masuda; H. Kikuchi (ISSP The University of Tokyo)
International Symposium of Quantum Beam Science at Ibaraki University 2023 (ISQBS2023), Nov. 2023, 茨城大学大学院理工学研究科量子線科学専攻
202411, 202411

Relationship between crystal structure and superconductivity in La3Co4Sn13-xInx
Y. Uramoto; K. Iwasa; T. Kumada; W. Kurosawa; Y. Suzuki; K. Suzumura; K. Tsuge; K. Kuwahara; D. Okuyama (Ibaraki University); H. Sagayama; H. Nakao (IMSS KEK); M. Ishikado (CROSS)
International Symposium of Quantum Beam Science at Ibaraki University 2023 (ISQBS2023), Nov. 2023, 茨城大学大学院理工学研究科量子線科学専攻
202411, 202411

原子科学研究教育センターと量子ビーム物性科学　　　　　　　　　　　　　　　
岩佐和晃
令和６年度茨城⼤学教育研究助成会春季理事会, Jun. 2024, [Invited]
202406, 202406

Nd3Rh4Sn13のカイラル対称結晶構造相における磁気秩序と結晶場分裂状態　　　　　　　　　　　　　　　
岩佐和晃; 下田愛海; 桑原慶太郎; 佐賀山基; 中尾裕則; 石角元志; 河村聖子; 村井直樹; 大原高志; 中尾朗子; 南部雄亮
日本物理学会2024年春季大会, Mar. 2024
202403, 202403

La3Co4Sn13-xInxにおける結晶構造と超伝導の関係　　　　　　　　　　　　　　　
浦本結稜、今関啓雅、岩佐和晃、熊田隆伸、黒澤航海、鈴木陽太郎、鈴村貫太、告華連、桑原 慶太郎(茨城大学)、奥山大輔、佐賀山基、中尾裕則(KEK物構研)、石角元志(CROSS)
2023年度量子ビームサイエンスフェスタ（第15回MLFシンポジウム, 第41回PFシンポジウム）, Mar. 2024, KEK 物質構造科学研究所,J-PARCセンター,総合科学研究機構（CROSS）,PFユーザーアソシエーション（PF-UA）,J-PARC MLF利用者懇談会
202403, 202403

Gd3Co4Sn13における結晶構造相転移と磁気秩序の量子ビーム散乱研究　　　　　　　　　　　　　　　
鈴村貫太(茨城大学理学部)、岩佐和晃(茨城大学フロンティアセンター)、熊田隆伸、黒澤 航海、鈴木陽太郎(茨城大学大学院理工学研究科)、浦本結稜、告華連(茨城大学理学部)、桑原慶太郎、大山研司(茨城大学大学院理工学研究科)、佐賀山基、中尾裕則、奥山大輔(KEK 物質構造科学研究所)、石角元志(CROSS)
2023年度量子ビームサイエンスフェスタ（第15回MLFシンポジウム, 第41回PFシンポジウム）, Mar. 2024, KEK 物質構造科学研究所,J-PARCセンター,総合科学研究機構（CROSS）,PFユーザーアソシエーション（PF-UA）,J-PARC MLF利用者懇談会
202403, 202403

Tb3Co4Sn13の磁気秩序と構造相転移に関する量子ビーム散乱研究　　　　　　　　　　　　　　　
鈴木陽太郎、岩佐和晃、熊田隆伸、黒澤航海、浦本結稜、鈴村貫太、告華連、桑原慶太郎、大山研司(Ibaraki University)、佐賀山基、奥山大輔、中尾裕則(KEK)、石角元志(CROSS)
2023年度量子ビームサイエンスフェスタ（第15回MLFシンポジウム, 第41回PFシンポジウム）, Mar. 2024, KEK 物質構造科学研究所,J-PARCセンター,総合科学研究機構（CROSS）,PFユーザーアソシエーション（PF-UA）,J-PARC MLF利用者懇談会
202403, 202403

R3Co4Sn13 (R = Pr, Sm)の結晶構造相転移と磁性　　　　　　　　　　　　　　　
告華連(Faculty of Science; Ibaraki University)、岩佐和晃(Frontier Research center; Ibaraki University)、熊田隆伸、黒澤航海、鈴木陽太郎(Graduate School of Sci. and Eng.; Ibaraki University)、浦本結稜、鈴村貫太(Faculty of Science; Ibaraki University)、桑原慶太郎(Graduate School of Sci. and Eng.; Ibaraki University)、佐賀山基、奥山大輔(KEK IMSS)、石角元志(CROSS)
2023年度量子ビームサイエンスフェスタ（第15回MLFシンポジウム, 第41回PFシンポジウム）, Mar. 2024, KEK 物質構造科学研究所,J-PARCセンター,総合科学研究機構（CROSS）,PFユーザーアソシエーション（PF-UA）,J-PARC MLF利用者懇談会
202403, 202403

Nd-Ru-Sn系 Remeika相化合物における磁気フラストレーションの可能性　　　　　　　　　　　　　　　
黒澤航海、岩佐和晃、熊田隆伸、鈴木陽太郎、浦本結稜、鈴村貫太、告華連、下田愛海、今関啓雅、大山研司、桑原慶太郎(茨城大学)、佐賀山基、奥山大輔、中尾裕則(KEK物構研)、石角元志(総合科学研究機構)、益田隆嗣、浅井晋一郎、菊池帆高(東大物性研)
2023年度量子ビームサイエンスフェスタ（第15回MLFシンポジウム, 第41回PFシンポジウム）, Mar. 2024, KEK 物質構造科学研究所,J-PARCセンター,総合科学研究機構（CROSS）,PFユーザーアソシエーション（PF-UA）,J-PARC MLF利用者懇談会
202403, 202403

Nd3Rh4Sn13のカイラル対称結晶構造相における反強磁性　　　　　　　　　　　　　　　
岩佐和晃、下田愛海、桑原慶太郎(Ibaraki University)、佐賀山基、中尾 裕則(KEK)、石角元志(CROSS)、河村聖子、村井直樹、大原高志(J-PARC Center)、中尾朗子(CROSS)、南部雄亮(Tohoku Univ; JST)
2023年度量子ビームサイエンスフェスタ（第15回MLFシンポジウム, 第41回PFシンポジウム）, Mar. 2024, KEK 物質構造科学研究所,J-PARCセンター,総合科学研究機構（CROSS）,PFユーザーアソシエーション（PF-UA）,J-PARC MLF利用者懇談会
202403, 202403

Nd-Ru-Sn系における結晶構造と磁性　　　　　　　　　　　　　　　
黒澤航海; 岩佐和晃; 下田愛海; 熊田隆伸; 今関啓雅; 鈴木陽太郎; 桑原慶太郎; 佐賀山基; 奥山大輔; 石角元志
日本中性子科学会第23回年会, Sep. 2023, 日本中性子科学会
202309, 202309

Ce3T4Sn13(T=Co,Rh,Ir)のカイラル対称構造相における4f電子超格子　　　　　　　　　　　　　　　
岩佐和晃; 桑原慶太郎; 横山淳; 河村聖子; 村井直樹; 中島健次; 川崎郁斗; 藤森伸一; J.-M. Mignot; A. Gukasov; S. Raymond; P. Steffens; 松田達磨; 青木勇二; 山上浩志; D. T. Adroja; A. M. Strydom
日本中性子科学会第23回年会, Sep. 2023, 日本中性子科学会
202309, 202309

Remeika相化合物Eu3T4Sn13(T=Rh,Ir)のカイラル結晶構造と磁気秩序　　　　　　　　　　　　　　　
鈴木陽太郎; 熊田隆伸; 岩佐和晃; 下田愛海; 今関啓雅; 黒澤航海; 桑原慶太郎; 佐賀山基; 奥山大輔; 中尾裕則; 石角元志
日本中性子科学会第23回年会, Sep. 2023, 日本中性子科学会
202309, 202309

Nd3Tr4Sn13 (Tr = Co, Rh, Ir)の立方ロッド充填カイラル格子における磁気状態　　　　　　　　　　　　　　　
岩佐和晃
学術変革領域(A)「アシンメトリが彩る量子物質の可視化・設計・創出」A01・A02合同トピカルミーティング「アシンメトリ量子物質を如何に可視化するか？ 〜ミクロ測定とマクロ測定の連携による研究戦略〜」, Aug. 2023
202308, 202308

Neutron-Scattering Study for Antiferromagnetic Order in Zn-doped CeCoIn5
Kaede Inoh; Azumi Yashiro; Asuka Hosogai; Ryosuke Koizumi; Hideaki Ebisawa; Teppei Takahashi; Ikuto Kawasaki; Daisuke Okuyama; Hung-Cheng Wu; Taku J. Sato; Kazuaki Iwasa; Kenji Ohoyama; Stephane Raymond; Kenichi Tenya; Makoto Yokoyama
The International Conference in Strongly Correlated Electrons Systems SCES2023, Jul. 2023
202307, 202307

Chiral Crystal Structures and Magnetic Orderings in the Remeika Phase Compounds Eu3T4Sn13 (T = Rh and Ir
Takanobu Kumada; Yohtaroh Suzuki; Ami Shimoda; Hiromasa Imazeki; Wataru Kurosawa; Kazuaki Iwasa; Keitaro Kuwahara; Kenji Ohoyama; Akinori Hoshikawa; Toru Ishigaki; Hajime Sagayama; Daisuke Okuyama; Hironori Nakao; Motoyuki Ishikado
The International Conference in Strongly Correlated Electrons Systems SCES2023, Jul. 2023
202307, 202307

Weyl-Kondo Semimetal Behavior in the Chiral Structure Phase of Ce3Rh4Sn13
Kazuaki Iwasa; Kazuya Suyama; Seiko Ohira-Kawamura; Kenji Nakajima; Stéphane Raymond; Paul Steffens; Akira Yamada; Tatsuma D. Matsuda; Yuji Aoki; Ikuto Kawasaki; Shin-ichi Fujimori; Hiroshi Yamagami; Makoto Yokoyama
The International Conference in Strongly Correlated Electrons Systems SCES2023, Jul. 2023
202307, 202307

アシンメトリ量子系としてのRemeika相物質群と量子ビーム複合研究による可視化　　　　　　　　　　　　　　　
岩佐和晃
学術変革領域(A)「アシンメトリが彩る量子物質の可視化・設計・創出」キックオフミーティング, Jun. 2023
202306, 202306

〔Major achievements〕立方晶Nd3Rh4Sn13の磁気励起に見られる擬1次元量子スピン反強磁性　　　　　　　　　　　　　　　
下田愛海; 岩佐和晃; 桑原慶太郎; 石角元志; 河村聖子; 村井直樹; 星川晃範; 石垣徹; 中尾朗子,大原高志; 佐賀山基; 中尾裕則
日本物理学会2023年春季大会, Mar. 2023
202303, 202303

〔Major achievements〕中性子散乱で見るZnイオン置換したCeCoIn5の反強磁性構造関　　　　　　　　　　　　　　　
井能楓; 矢代安澄; 小泉遼介; 細貝明日香; 海老澤秀明; 高橋哲平; 川崎郁斗; 奥山大輔; Hung-Cheng Wu; 佐藤卓; 岩佐和晃; 大山研司; Stephane Raymond; 天谷健一; 横山淳
日本物理学会2023年春季大会, Mar. 2023
202303, 202303

カイラル結晶構造を持つY3Rh4Ge13 の低温物性測定と超伝導特性　　　　　　　　　　　　　　　
Afzal MD Asif; 東中隆二; 岩佐和晃; Nazir Ahmed; 坪田椋; 中村直貴; 松田達磨; 青木勇二
日本物理学会2024年春季大会, Mar. 2023
202303, 202303

La3Co4Sn13-xInxにおける結晶構造相転移と超伝導　　　　　　　　　　　　　　　
今関啓雅; 岩佐和晃; 下田愛海; 熊田隆伸; 黒澤航海; 鈴木陽太郎; 桑原慶太郎; 佐賀山基; 中尾裕則; 奥山大輔; 石角元志
2022年度量子ビームサイエンスフェスタ（第14回MLFシンポジウム, 第40回PFシンポジウム）, Mar. 2023, KEK 物質構造科学研究所,J-PARCセンター,総合科学研究機構（CROSS）,PFユーザーアソシエーション（PF-UA）,J-PARC MLF利用者懇談会
202303, 202303

Nd-Ru-Sn系における結晶構造と磁性　　　　　　　　　　　　　　　
黒澤航海; 岩佐和晃; 下田愛海; 熊田隆伸; 今関啓雅; 鈴木陽太郎; 桑原慶太郎; 佐賀山基; 奥山大輔; 石角元志
2022年度量子ビームサイエンスフェスタ（第14回MLFシンポジウム, 第40回PFシンポジウム）, Mar. 2023, KEK 物質構造科学研究所,J-PARCセンター,総合科学研究機構（CROSS）,PFユーザーアソシエーション（PF-UA）,J-PARC MLF利用者懇談会
202303, 202303

Eu3Ir4Sn13おける結晶構造相転移と反強磁気秩序の量子ビーム散乱研究　　　　　　　　　　　　　　　
鈴木陽太郎; 熊田隆伸; 岩佐和晃; 下田愛海; 今関啓雅; 黒澤航海; 桑原慶太郎; 佐賀山基; 奥山大輔; 中尾裕則; 石角元志
2022年度量子ビームサイエンスフェスタ（第14回MLFシンポジウム, 第40回PFシンポジウム）, Mar. 2023, KEK 物質構造科学研究所,J-PARCセンター,総合科学研究機構（CROSS）,PFユーザーアソシエーション（PF-UA）,J-PARC MLF利用者懇談会
202303, 202303

茨城大学によるJRR-3 HQR を含む量子ビーム利用による 研究・教育活動　　　　　　　　　　　　　　　
岩佐和晃; 大山研司; 横山淳; 中野岳仁; 桑原慶太郎; 伊賀文俊; 中島多朗
2022年度量子ビームサイエンスフェスタ（第14回MLFシンポジウム, 第40回PFシンポジウム）, Mar. 2023, KEK 物質構造科学研究所,J-PARCセンター,総合科学研究機構（CROSS）,PFユーザーアソシエーション（PF-UA）,J-PARC MLF利用者懇談会
202303, 202303

パラレルセッション（6会場）のまとめ「C会場（高圧、 構造物性、 固体分光、 核共鳴散乱、 動的構造）報告」
岩佐和晃
PF研究会「開発研究多機能ビームラインの建設と利用」②, Jan. 2023, 高エネルギー加速器研究機構
202301, 202301

カイラル構造相転移物質における電子物性の量子ビーム散乱研究　　　　　　　　　　　　　　　
岩佐和晃
公益財団法人山田科学振興財団2022年度研究交歓会, Oct. 2022, 公益財団法人山田科学振興財団
202210, 202210

東北大学中性子散乱分光器6G TOPANの2022年　　　　　　　　　　　　　　　
池田 陽一,大河原 学,高田 秀佐,南部 雄亮,谷口 貴紀,藤田 全基,岩佐 和晃
日本中性子科学会第22回年会, Oct. 2022, 日本中性子科学会
202210, 202210

Nd3Tr4Sn13 (Tr = Rh, Ir)の立方ロッド充填格子における磁気状態　　　　　　　　　　　　　　　
岩佐和晃; 下田愛海; 桑原慶太郎; 石角元志,河村聖子; 村井直樹; 星川晃範; 石垣徹; 中尾朗子; 大原高志; 佐賀山基; 中尾裕則
日本中性子科学会第22回年会, Oct. 2022, 日本中性子科学会
202210, 202210

Educational use of neutron triple axis spectrometer　　　　　　　　　　　　　　　
Kazuaki Iwasa
Neutron Scattering on continuous sources – future developments. US-Japan workshop (Focus Sessions Topics Hard Condensed Matter), Sep. 2022, Oak Ridge National Laboratory
202209, 202209

〔Major achievements〕一次元反強磁性体CuX2・(γ-pic)2(X=Cl,Br)の磁性と結晶構造との相関　　　　　　　　　　　　　　　
浅野貴行; 西首時夫; 三田魁斗; 神戸高志; 岩佐和晃; 佐賀山基; 鳴海康雄; 萩原政幸; 梅野智大; 臼井一晃; 唐沢悟
日本物理学会2022年秋季大会, Sep. 2022
202209, 202209

〔Major achievements〕Nd3T4Sn13 (T=Rh, Ir)におけるカイラル対称結晶構造相転移と反強磁気秩序　　　　　　　　　　　　　　　
下田愛海; 岩佐和晃; 桑原慶太郎; 星川晃範; 石垣徹; 中尾裕則; 佐賀山基; 大原高志; 中尾朗子; 石角元志
日本物理学会2022年秋季大会, Sep. 2022
202209, 202209

〔Major achievements〕単結晶中性子回折によるNdCo2Zn20の磁気構造の研究　　　　　　　　　　　　　　　
山本理香子; 岩佐和晃; 大山研司; 鬼丸孝博
日本物理学会2022年秋季大会, Sep. 2022
202209, 202209

〔Major achievements〕Magnetic ordering and structural phase transitions of Nd3T4Sn13 (T = Rh and Ir)　　　　　　　　　　　　　　　
Ami Shimoda; Kazuaki Iwasa; Keitaro Kuwahara; Hajime Sagayama; Hironori Nakao; Motoyuki Ishikado; Takashi Ohhara; Akiko Nakao; Akinori Hoshikawa; and Toru Ishigaki
29th International Conference on Low Temperature Physics (LT29),, Aug. 2022
202208, 202208

Inelastic Neutron Scattering Spectrometers in JRR-3　　　　　　　　　　　　　　　
Takatsugu Masuda; Taro Nakajima; Taku J Sato; Yusuke Nambu; Masaaki Fujita; Kenji Ohoyama; Kazuaki Iwasa; Osamu Yamamuro; Toyotaka Osakabe; Koji Kaneko; Hiroki Yamauchi; and Masayasu Takeda
The 15th Edition of the QENS series and the 10th of the WINS workshops, May 2022
202205, 202205

Ce3T4Sn13 (T = 遷移金属)の量子ビーム散乱構造物性　　　　　　　　　　　　　　　
岩佐和晃
東京大学物性研究所短期研究会「中性子散乱研究会 - 海外実験支援プログラムの成果報告と、再稼働したJRR-3の現在地 -」, Apr. 2022, 東京大学物性研究所, [Invited]
202204, 202204

再稼働した汎用中性子三軸分光器T1-1(HQR)の性能評価　　　　　　　　　　　　　　　
富松優花; Keiko Widyanisa; 小林洋大; 岩佐和晃; 中島多朗; 大山研司
日本物理学会第77回年会, Mar. 2022
202203, 202203

La3T4Sn13 (T = Co, Rh)への遷移金属元素置換によるカイラル構造の量子臨界と超伝導　　　　　　　　　　　　　　　
岩佐和晃; 塩澤真未; 橋本大輔; 鈴木詩織; 郡司和毅; 下田愛海; 桑原慶太郎; 佐賀山基; 中尾裕則; 石角元志
日本物理学会第77回年会, Mar. 2022
202203, 202203

La3Co4Sn13における結晶構造相転移と超伝導　　　　　　　　　　　　　　　
西口日向; 岩佐和晃; 下田愛海; 熊田隆伸; 尾本星太; 桑原慶太郎; 佐賀山基; 石角元志
2021年度量子ビームサイエンスフェスタ（第13回MLFシンポジウム, 第39回PFシンポジウム）, Mar. 2022, KEK 物質構造科学研究所,J-PARCセンター,総合科学研究機構（CROSS）,PFユーザーアソシエーション（PF-UA）,J-PARC MLF利用者懇談会
202203, 202203

Nd3T4Sn13 (T = Rh, Ir)におけるカイラル結晶構造相転移と反強磁気秩序　　　　　　　　　　　　　　　
下田愛海; 岩佐和晃; 桑原慶太郎; 佐賀山基; 中尾裕則; 石角元志; 大原高志; 中尾朗子
2021年度量子ビームサイエンスフェスタ（第13回MLFシンポジウム, 第39回PFシンポジウム）, Mar. 2022, KEK 物質構造科学研究所,J-PARCセンター,総合科学研究機構（CROSS）,PFユーザーアソシエーション（PF-UA）,J-PARC MLF利用者懇談会
202203, 202203

Eu3Rh4Sn13の結晶構造相転移と反強磁気秩序の量子ビーム散乱研究　　　　　　　　　　　　　　　
熊田隆伸; 岩佐和晃; 下田愛海; 尾本星太; 西口日向; 桑原慶太郎; 佐賀山基; 中尾裕則; 石角元志
2021年度量子ビームサイエンスフェスタ（第13回MLFシンポジウム, 第39回PFシンポジウム）, Mar. 2022, KEK 物質構造科学研究所,J-PARCセンター,総合科学研究機構（CROSS）,PFユーザーアソシエーション（PF-UA）,J-PARC MLF利用者懇談会
202203, 202203

Gd3Ir4Sn13の単結晶合成と放射光Ｘ線回折による構造相転移の研究　　　　　　　　　　　　　　　
尾本星太; 岩佐和晃; 下田愛海; 熊田隆伸; 西口日向; 桑原慶太郎; 佐賀山基; 中尾裕則; 石角元志
2021年度量子ビームサイエンスフェスタ（第13回MLFシンポジウム, 第39回PFシンポジウム）, Mar. 2022, KEK 物質構造科学研究所,J-PARCセンター,総合科学研究機構（CROSS）,PFユーザーアソシエーション（PF-UA）,J-PARC MLF利用者懇談会
202203, 202203

Magnetic states in chiral-structure phase of Ce3Ir4Sn13
岩佐 和晃; 中里 晟也; 橋本 大輔; 塩澤 真未; 桑原 慶太郎; 佐賀山 基; 河村 聖子; 村井 直樹; Devashibhai T. Adroja; Andre M. Strydom
日本中性子科学会第21回年会, Dec. 2021, 日本中性子科学会
202112, 202112

Present status of the triple-axis spectrometer, T1-1 (HQR)
富松 優花, Keiko Widyanisa, 小林 洋大, 岩佐 和晃, 中島 多朗, 大山 研司
日本中性子科学会第21回年会, Dec. 2021, 日本中性子科学会
202112, 202112

Current status of 6G-TOPAN in 2021
池田陽一,大河原学,谷口貴紀,南部雄亮,岩佐和晃,藤田全基
日本中性子科学会第21回年会, Dec. 2021, 日本中性子科学会
202112, 202112

Present status of the triple-axis spectrometer, T1-1 (HQR)
大山 研司; 岩佐 和晃; 中島 多朗; 伊賀 文俊; 桑原 慶太郎; 中野 岳仁; 横山 淳
日本中性子科学会第21回年会, Dec. 2021, 日本中性子科学会
202112, 202112

Superconductivity enhancement and quantum critical point of chiral structure induced by atomic substitutions in La3T4Sn13 (T = Co and Rh)　　　　　　　　　　　　　　　
Kazuaki Iwasa; Mami Shiozawa; Daisuke Hashimoto; Shiori Ssuzuki; Kazuki Gunji; Ami Shimoda; Keitaro Kuwahara; Hajime Sagayama; Hironori Nakao; Motoyuki Ishikado
International Conference on Strongly Correlated Electron Systems SCES2020/21, Sep. 2021
202109, 202110

La3Ir4Sn13におけるカイラル構造相転移と超伝導　　　　　　　　　　　　　　　
岩佐和晃; 中里晟也; 塩澤真未; 橋本大輔; 桑原慶太郎; 髭本亘; 伊藤孝; 中尾裕則; 佐賀山基; 石角元志
日本物理学会2021年秋季大会, Sep. 2021
202109, 202109

一次元反強磁性体CuX2・(γ-pic)2(X=Cl,Br)の磁性と誘電性　　　　　　　　　　　　　　　
浅野貴行; 西首時夫; 神戸高志; 鳴海康雄; 萩原政幸; 梅野智大; 臼井一晃; 唐沢悟; 岩佐和晃
日本物理学会2021年秋季大会, Sep. 2021
202109, 202109

Nd3Rh4Sn13におけるカイラル結晶構造相転移と反強磁気秩序　　　　　　　　　　　　　　　
下田愛海; 桑原慶太郎; 中尾裕則; 佐賀山基; 大原高志; 中尾朗子; 石角元志; 岩佐和晃
日本物理学会2021年秋季大会, Sep. 2021
202109, 202109

Ce3Rh4Sn13へのRu置換によるカイラル構造量子臨界点　　　　　　　　　　　　　　　
橋本大輔; 岩佐和晃; 中里晟也; 塩澤真未; 郡司和毅; 下田愛海; 鈴木詩織,桑原慶太郎; 石角元志; 中尾裕則; 佐賀山基(KEK物構研); 河村聖子; 村井直樹; 中島健次
日本物理学会第76回年次大会, Mar. 2021
202103, 202103

カイラル構造相転移をする超伝導体La3(Co1-xFex)4Sn13とLa3(Co1-xRhx)4Sn13の元素置換効果　　　　　　　　　　　　　　　
塩澤真未; 鈴木詩織; 岩佐和晃; 下田愛海; 中里晟也; 橋本大輔; 郡司和毅; 桑原慶太郎; 石角元志; 中尾裕則; 佐賀山基; 髭本亘; 伊藤孝
日本物理学会第76回年次大会, Mar. 2021
202103, 202103

レーザー角度分解光電子分光による Ce モノプニクタイドの多体相互作用の観測　　　　　　　　　　　　　　　
新井陽介; 黒田健太; 野本拓也; 黒川輝風; 辛埴; 久保田正人; 芳賀芳範; 鈴木博之; 岩佐和晃; 有田亮太郎; 近藤猛
日本物理学会第76回年次大会, Mar. 2021
202103, 202103

クロミック物質CoMoO4の不整合−整合磁気秩序相転移　　　　　　　　　　　　　　　
岩佐和晃、星川晃範、松川健、石垣徹、浅野貴行、稲垣祐次、河江達也
日本物理学会第76回年次大会, Mar. 2021
202103, 202103

クロミック物質CoMoO4の不整合−整合磁気秩序相転移　　　　　　　　　　　　　　　
岩佐和晃、星川晃範、松川健、石垣徹、浅野貴行、稲垣祐次、河江達也
日本物理学会第76回年次大会, Mar. 2021, KEK 物質構造科学研究所,J-PARCセンター,総合科学研究機構（CROSS）,PFユーザーアソシエーション（PF-UA）,J-PARC MLF利用者懇談会
202103, 202103

クロミック物質CoMoO4の不整合−整合磁気秩序相転移　　　　　　　　　　　　　　　
岩佐和晃、星川晃範、松川健、石垣徹、浅野貴行、稲垣祐次、河江達也
2020年度量子ビームサイエンスフェスタ（第12回MLFシンポジウム, 第38回PFシンポジウム）, Mar. 2021, KEK 物質構造科学研究所,J-PARCセンター,総合科学研究機構（CROSS）,PFユーザーアソシエーション（PF-UA）,J-PARC MLF利用者懇談会
202103, 202103

Search for unconventional correlated electrons under chiral symmetry in rare-earth intermetallics　　　　　　　　　　　　　　　
K. Iwasa
The 5th International Symposium of Quantum Beam Science at Ibaraki University - Chirality in Materials Science: Current Status and Future Prospects -, Nov. 2020, 茨城大学大学院理工学研究科量子線科学専攻, [Invited]
202011, 202011

Crystal structure and magnetic property of Nd3Rh4Sn13: a possible chiral magnet　　　　　　　　　　　　　　　
Ami Shimoda; Kazuaki Iwasa
The 5th International Symposium of Quantum Beam Science at Ibaraki University - Chirality in Materials Science: Current Status and Future Prospects -, Nov. 2020, 茨城大学大学院理工学研究科量子線科学専攻, [Invited]
202011, 202011

Atomic substitution effect on chiral structure and superconductivity of La3(Co1-xFex)4Sn13 and La3(Co1-xRux)4Sn13　　　　　　　　　　　　　　　
Mami Shiozawa; Shiori Suzuki; K. Iwasa; A. Shimoda; D. Hashimoto; K. Gunji; S. Nakazato; K.Kuwahara; M. Ishikado; H. Nakao; H. Sagayama; W. Higemoto; T.U. Ito
The 5th International Symposium of Quantum Beam Science at Ibaraki University - Chirality in Materials Science: Current Status and Future Prospects -, Nov. 2020, 茨城大学大学院理工学研究科量子線科学専攻, [Invited]
202011, 202011

Ru-substitution effect on structural transitions and electronic states in chiral materials Ce3Rh4Sn13 and La3Rh4Sn13　　　　　　　　　　　　　　　
Daisuke Hashimoto; Kazuki Gunji; K. Iwasa; S. Nakazato; M. Shiozawa; A. Shimoda; S. Suzuki; K. Kuwahara; M. Ishikado; H. Nakao; H. Sagayama; S. Ohira-Kawamura; N. Murai; K. Nakajima
The 5th International Symposium of Quantum Beam Science at Ibaraki University - Chirality in Materials Science: Current Status and Future Prospects -, Nov. 2020, 茨城大学大学院理工学研究科量子線科学専攻, [Invited]
202011, 202011

Incommensurate–Commensurate Magnetic Phase transition ,in Chromic Material CoMoO4
岩佐和晃; 星川晃範; 松川健; 石垣徹; 茨城大フロンティアセ; 浅野貴行; 大; 稲垣祐次; 河江達也
日本中性子科学会第20回年会, Nov. 2020, 日本中性子科学会
202011, 202011

Ce3Ir4Sn13におけるカイラル構造相転移と磁気状態　　　　　　　　　　　　　　　
岩佐和晃; 中里晟也; 橋本大輔; 塩澤真未; 桑原慶太郎; 中尾裕則; 佐賀山基; 石角元志; 大原高志; 中尾朗子; 宗像孝司; 鬼柳亮嗣; F. Damay; J.-M. Mignot; 河村聖子; 村井直樹; 中島健次
日本物理学会 2020年秋季大会, Sep. 2020, 日本物理学会
202009, 202009

反強磁性体CeSbの「悪魔の階段」と共に発達する磁気ポーラロン状態の観測　　　　　　　　　　　　　　　
新井陽介; 黒田健太; 野本拓也; Z. H. Tin; 櫻木俊輔; C. Bareille; 明比俊太朗; 黒川輝風; 木下雄斗; W. L; Zhang; 辛埴; 徳永将史; 宮坂茂樹; 田島節子; 芳賀芳範; 北澤英明; 鈴木博之; 岩佐和晃; 有田亮太郎; 近藤猛
日本物理学会 2020年秋季大会, Sep. 2020, 日本物理学会
202009, 202009

カイラル半金属Ce3Rh4Sn13の構造相転移と磁性におけるRu置換効果の研究　　　　　　　　　　　　　　　
橋本大輔; 岩佐和晃; 中里晟也; 塩澤真未; 桑原慶太郎; 石角元志; 中尾裕則; 佐賀山基; 河村聖子; 村井直樹; 中島健次
日本物理学会 2020年秋季大会, Sep. 2020, 日本物理学会
202009, 202009

La3(Co1-xFex)4Sn13のカイラル構造相転移と超伝導　　　　　　　　　　　　　　　
塩澤真未; 岩佐和晃; 中里晟也; 橋本大輔; 桑原慶太郎; 石角元志; 中尾裕則; 佐賀山基; 髭本亘; 伊藤孝
日本物理学会 2020年秋季大会, Sep. 2020, 日本物理学会
202009, 202009

キラル構造を持つ超伝導体La3Co4Sn13および関連物質のNQR測定による研究　　　　　　　　　　　　　　　
永瀬裕也; 真砂全宏; 小手川恒; 藤秀樹; 塩沢夏未; 橋本大輔; 中里晟也; 岩佐和晃
日本物理学会 2020年秋季大会, Sep. 2020, 日本物理学会
202009, 202009

Chiral structural phase transition and electronic state in Ce3T4Sn13 (T = Co, Rh, Ru, Ir)
岩佐和晃
東京大学物性研究所短期研究会, Jul. 2020, 東京大学物性研究所, [Invited]
202007, 202007

Effects of chiral-crystal-structure transformations on magnetic states and superconductivity in R3T4Sn13 (R = La and Ce, T = transition metal)
Kazuaki Iwasa
Virtual Theoretical & Experimental Magnetism Meeting (vTEMM) 2020 and UK-Japan Workshop on Strongly ​​Correlated Electron Systems, Jul. 2020, - ISIS Pulsed Neutron and Muon Source,- Institut Laue-Langevin,- The Institue of Physics Magnetism and Neutron Scattering Groups,- The Japan Society for the Promotion of Science (JSPS),- Max Planck Institute for the Physics of Complex Systems, [Invited]
202007, 202007

Successive phase transitions of Kondo semimetal Ce3Ir4Sn13
中里晟也; 岩佐和晃; 茨城大フロンティアセンター; 橋本大輔; 塩澤真未; 桑原慶太郎; 中尾裕則; 佐賀山基(K; 石角元志(CROSS; 大原高志; PARCセンター; 中尾朗子; 宗像孝司(CROSS; 鬼柳亮嗣; PARCセンター; F. Damay; J.-M. Migno
日本物理学会 第75回年次大会, Mar. 2020, 日本物理学会
202003, 202003

Observation of Raman scattering from vibronic mode and electron-mode coupling,investigated by laser-ARPES in CeSb
新井陽介; 黒田健太; 櫻木俊輔; Z.H. Ti; W. Zhang; 東大物性; 上智大理工; 岩佐和晃; 茨城大フロンティアセ; 芳賀芳範; 鈴木博之; 北澤英明; 辛埴(東大特; 宮坂茂樹; 田島節子; 近藤猛
日本物理学会 第75回年次大会, Mar. 2020, 日本物理学会
202003, 202003

p-f hybridization in PrFe4P12 investigated by resonant X-ray scattering
中尾裕則; 岩佐和晃; 茨城大フロンティアセンター
日本物理学会 第75回年次大会, Mar. 2020, 日本物理学会
202003, 202003

Short range correlation of low-temperature chiral lattice structure,in superconductor La3(Co1-xFex)4Sn13
塩澤真未; 岩佐和晃; 茨城大フロンティアセンター; 中里晟也; 橋本大輔; 桑原慶太郎; 石角元志(CROSS; 中尾裕則; 佐賀山基; KEK物構研
日本物理学会 第75回年次大会, Mar. 2020, 日本物理学会
202003, 202003

Ru-substitution effect on structural transition and magnetism of chiral semimetal Ce3Rh4Sn13
橋本大輔; 岩佐和晃; 茨城大フロンティアセンター; 中里晟也; 塩澤真未; 桑原慶太郎; 石角元志(CROSS; 中尾裕則; 佐賀山基
日本物理学会 第75回年次大会, Mar. 2020, 日本物理学会
202003, 202003

Neutron Diffraction of Chromic Material CoMoO4
岩佐和晃; 星川晃範; 松川健; 石垣徹; 茨城大フロンティアセ; 浅野貴行; 稲垣祐次; 河江達也
2019年度量子ビームサイエンスフェスタ（第11回MLFシンポジウム, 第37回PFシンポジウム）, Mar. 2020, KEK物質構造科学研究所、J-PARCセンター、総合科学研究機構（CROSS）、PFユーザーアソシエーション（PF-UA）、J-PARC MLF利用者懇談会
202003, 202003

p-f hybridization in PrFe4P12 investigated, by resonant X-ray scattering
中尾裕則; EK物構研; 岩佐和晃; 茨城大フロンティアセンター
2019年度量子ビームサイエンスフェスタ（第11回MLFシンポジウム, 第37回PFシンポジウム）, Mar. 2020, KEK物質構造科学研究所、J-PARCセンター、総合科学研究機構（CROSS）、PFユーザーアソシエーション（PF-UA）、J-PARC MLF利用者懇談会
202003, 202003

Short range correlation of low-temperature chiral lattice structure in superconductor La3(Co1-xFex)4Sn13
塩澤真未; 城大院理工; 岩佐和晃; 茨城大学フロンティアセンター; 中里晟也; 橋本大輔; 桑原慶太郎; 石角元志(CROSS; 中尾裕則; 佐賀山基
2019年度量子ビームサイエンスフェスタ（第11回MLFシンポジウム, 第37回PFシンポジウム）, Mar. 2020, KEK物質構造科学研究所、J-PARCセンター、総合科学研究機構（CROSS）、PFユーザーアソシエーション（PF-UA）、J-PARC MLF利用者懇談会
202003, 202003

Ru-substitution effect on structural transition and magnetism of chiral semimetal Ce3Rh4Sn13
橋本大輔; 城大院理工; 岩佐和晃; 茨城大学フロンティアセンター; 中里晟也; 塩澤真未; 桑原慶太郎; 石角元志(CROSS; 中尾裕則; 佐賀山基
2019年度量子ビームサイエンスフェスタ（第11回MLFシンポジウム, 第37回PFシンポジウム）, Mar. 2020, KEK物質構造科学研究所、J-PARCセンター、総合科学研究機構（CROSS）、PFユーザーアソシエーション（PF-UA）、J-PARC MLF利用者懇談会
202003, 202003

Semimetal and Superconductivity in Chiral-structure Phase of R3T4Sn13 (R = Ce, La and T = Co, Rh, Ir)　　　　　　　　　　　　　　　
Kazuaki IWASA; Yuka OTOMO; Kazuya SUYAMA; Ryoga KARINO; Kango MIYAKAWA; Seiya NAKAZATO; Daisuke HASHIMOTO; Mami SHIOZAWA; Keitaro KUWAHARA; Motoyuki ISHIKADO; Hajime SAGAYAMA; Hironori NAKAO; Seiko OHIRA-KAWAMURA; Tatsuya KIKUCHI; Kenji NAKAJIMA; Takashi OHHARA; Akiko NAKAO; Koji MUNAKATA; Ryoji KIYANAGI; Jean-Michel MIGNOT; Françoise DAMAY; Arsen GUKASOV
Materials Research Meeting 2019, Dec. 2019, MRS-Japan (The Materials Research Society of Japan

Improvement of X-ray fluorescence holography instrument and measurement of Ce3Co4Sn13 at cryogenic temperature
Ryota Yamaguchi; Naohisa Happo; Kazuaki Iwasa; Shinya Hosokawa; Koichi Hayashi; Koji Kimura; Yuta Yamamoto; Kazushi Miki; Kotaro Nawata
The International Workshop on Electronics, Information and Communication（IWEIC2019）, Nov. 2019, 広島市立大学

Dimensional Crossover of Magnetic Correlation and Chiral-lattice Criticality in Ce3(Rh1-xRux)4Sn13　　　　　　　　　　　　　　　
Kazuaki Iwasa
The 4th International Symposium of Quantum Beam Science at Ibaraki University, Oct. 2019, 茨城大学大学院理工学研究科量子線科学専攻, [Invited]

Short Range Correlation of Chiral Lattice Structure in Superconductor La3(Co1-xFex)4Sn13　　　　　　　　　　　　　　　
M. Shiozawa; K. Iwasa; S. Nakazato; D. Hashimoto; K. Kuwahara; M. Ishikado; H. Nakao; H. Sagayama
The 4th International Symposium of Quantum Beam Science at Ibaraki University, Oct. 2019, 茨城大学大学院理工学研究科量子線科学専攻, [Invited]

Quantum-beam scattering studies on structural phase transition and magnetism of R3Ir4Sn13 (R = La, Ce)　　　　　　　　　　　　　　　
S. Nakazato; K. Iwasa; M. Shiozawa; D. Hashimoto; K. Kuwahara; H. Nakao; H. Sagayama; M. Ishikado; J.-M. Mignot
The 4th International Symposium of Quantum Beam Science at Ibaraki University, Oct. 2019, 茨城大学大学院理工学研究科量子線科学専攻, [Invited]

Ru-substitution effect on structural transition and magnetism of chiral semimetal Ce3Rh4Sn13　　　　　　　　　　　　　　　
D. Hashimoto; K. Iwasa; S. Nakazato; M. Shiozawa; K. Kuwahara; M. Ishikado; H. Nakao; H. Sagayama
The 4th International Symposium of Quantum Beam Science at Ibaraki University, Oct. 2019, 茨城大学大学院理工学研究科量子線科学専攻, [Invited]

Magnetic and structural study on semimetal Ce3Ru4Sn13 synthesized using a molten Sn-flux method　　　　　　　　　　　　　　　
Kazuaki Iwasa; Ryoga Karino; Kango Miyakawa; Daisuke Hashimoto; Mami Shiozawa; Seiya Nakazato; Keitaro Kuwahara; Motoyuki Ishikado; Hajime Sagayama; Seiko Ohira-Kawamura; Tatsuya Kikuchi; Kenji Nakajima
The International Conference on Strongly Correlated Electron Systems 2019, Sep. 2019

Successive phase transitions in R3Ir4Sn13 (R: La and Ce) investigated using neutron and x-ray diffraction　　　　　　　　　　　　　　　
S. Nakazato; K. Iwasa; D. Hashimoto; M. Shiozawa; K. Kuwahara; H. Nakao; H. Sagayama; M. Ishikado; T. Ohhara; A. Nakao; K. Munakata; and R. Kiyanagi
The International Conference on Strongly Correlated Electron Systems 2019, Sep. 2019

半金属物質Ce3Ru4Sn13における一次元反強磁性　　　　　　　　　　　　　　　
岩佐和晃; 狩野遼河; 宮川貫伍; 中里晟也; 橋本大輔; 塩澤真未; 桑原慶太郎; 石角元志; 佐賀山基; 河村聖子; 菊地龍弥; 中島健次
日本物理学会 2019年秋季大会, Sep. 2019, 日本物理学会

中性子散乱からみたTbNiC2 における電荷密度波と磁性の相関　　　　　　　　　　　　　　　
田端千紘; Xavier Fabreges; Arsen Goukassov; 山本将隆; 村田怜也; 網塚浩; 中尾裕則; 岩佐和晃; 下村晋; 小野寺秀也
日本物理学会 2019年秋季大会, Sep. 2019, 日本物理学会

クロミック物質CoMoO4の磁性　　　　　　　　　　　　　　　
浅野貴行; 横山太紀; 稲垣裕次; 河江達也; 神戸高志; 鳴海康雄; 萩原政幸; 岩佐和晃; 星川晃範; 松川健; 石垣徹; 菊池彦光
日本物理学会 2019年秋季大会, Sep. 2019, 日本物理学会

CeSbのレーザーARPESスペクトルにおけるキンク構造　　　　　　　　　　　　　　　
新井陽介; 黒田健太; 櫻木俊輔; 國定聡; 岩佐和晃; 芳賀芳範; 鄭子豪; 宮坂茂樹; 田島節子; 北澤英明; 辛埴; 鈴木博之; 近藤猛
日本物理学会 2019年秋季大会, Sep. 2019, 日本物理学会

PrRu4P12の秩序相におけるp-f混成の変調構造の共鳴X線散乱による観測　　　　　　　　　　　　　　　
中尾裕則; 田端千紘; 岩佐和晃
日本物理学会第74回年次大会（2019.3.14-3.17）, Mar. 2019, 日本物理学会

Yb3Ir4Ge13における少数キャリアー半金属状態と反強磁気ゆらぎ　　　　　　　　　　　　　　　
岩佐和晃; C.-L. Huang; Binod K. Rai; E. Morosan; 河村聖子; 中島健次
日本物理学会第74回年次大会（2019.3.14-3.17）, Mar. 2019, 日本物理学会

レーザー角度分解光電子分光で観測するCeSbの電子格子結合　　　　　　　　　　　　　　　
新井陽介; 黒田健太; 岩佐和晃; N. Rezaei; 鈴木博之; 芳賀芳範; 国定聡; 櫻木俊輔; 明比俊太朗; M. Alaei; 北澤英明; 辛埴; 有田亮太郎; 近藤猛
日本物理学会第74回年次大会（2019.3.14-3.17）, Mar. 2019, 日本物理学会

R3T4Sn13 (R = La, Ce; T = Ir, Ru)の構造相転移と磁性の量子ビーム散乱研究　　　　　　　　　　　　　　　
中里晟也; 岩佐和晃; 狩野遼河; 宮川貫伍; 塩澤真未; 橋本大輔; 桑原慶太郎; 中尾裕則; 河村聖子; 中島健次; Jean-Michel Mignot
日本物理学会第74回年次大会（2019.3.14-3.17）, Mar. 2019, 日本物理学会

Quantum-beam scattering studies on structural phase transition and magnetism of R3T4Sn13 (R = La, Ce; T = Ir, Ru)　　　　　　　　　　　　　　　
中里晟也; 岩佐和晃; 狩野遼河; 宮川貫伍; 塩澤真未; 橋本大輔; 桑原慶太郎; 中尾裕則; 河村聖子; 中島健次; Jean-Michel Mignot
2018年度量子ビームサイエンスフェスタ（第10回MLFシンポジウム, 第36回PFシンポジウム）, Mar. 2019, KEK物質構造科学研究所, J-PARCセンター

Magnetic fluctuation in low-carrier density semimetal Yb3Ir4Ge13　　　　　　　　　　　　　　　
岩佐和晃; C.-L. Huang; Binod K. Rai; E. Morosan; 河村聖子; 中島健次
2018年度量子ビームサイエンスフェスタ（第10回MLFシンポジウム, 第36回PFシンポジウム）, Mar. 2019, KEK物質構造科学研究所, J-PARCセンター

Modulation of p-f hybridization in unconventional ordered phase of PrRu4P12 studied by resonant X-ray scattering　　　　　　　　　　　　　　　
中尾裕則; 田端千紘; 岩佐和晃
2018年度量子ビームサイエンスフェスタ（第10回MLFシンポジウム, 第36回PFシンポジウム）, Mar. 2019, KEK物質構造科学研究所, J-PARCセンター

Ce3Tr4Sn13 (Tr: Co, Ru, Rh)の半金属状態における結晶構造と磁気状態の量子ビーム散乱研究　　　　　　　　　　　　　　　
岩佐和晃; 茨城大フロンティアセ; 狩野遼河; 宮川貫伍; 桑原慶太郎; 佐賀山基; 佐賀山遼子; 熊井玲児(K; 河村聖子; 菊地龍弥; 中島健次; PARCセンター
日本物理学会2018年秋季大会, Sep. 2018, 日本物理学会

Neutron and x-ray scattering studies on semimetal systems Ce3Tr4Sn13 (Tr: transition metal)　　　　　　　　　　　　　　　
Kazuaki Iwasa(Ibaraki Univ.)
東京大学物性研究所短期研究会「固体物性の中性子散乱研究の現在と将来 ～日米協力事業の今後を見据えて～」, Jun. 2018, 東京大学物性研究所, [Invited]

TbB6における磁気−構造相転移の再検証　　　　　　　　　　　　　　　
岩佐和晃; 茨城大フロンティアセ; 伊賀文俊; 茂吉武人; 中尾朗子(CROSS; 大原高志
日本物理学会第73回年次大会, Mar. 2018, 日本物理学会

Chiral Crystal-Structure Transformation and Magnetic Excitation in Ce3Tr4Sn13　　　　　　　　　　　　　　　
岩佐和晃; 大友優香; 巣山和哉; 富安啓輔; 狩野遼河; 宮川貫伍; 佐賀山基; 佐賀山遼子; 中尾裕則; 熊井玲児; 村上洋一; 河村聖子; 中島健次; J.-M. Mignot; A. Gukasov; B. Gillon; S. Raymond; P. Steffens
2017年度量子ビームサイエンスフェスタ（第9回MLFシンポジウム, 第35回PFシンポジウム）, Mar. 2018, KEK物質構造科学研究所, J-PARCセンター

Unconventional order phase of PrRu4P12 studied by resonant x-ray scattering　　　　　　　　　　　　　　　
中尾裕則; 田端千紘; 岩佐和晃
2017年度量子ビームサイエンスフェスタ（第9回MLFシンポジウム, 第35回PFシンポジウム）, Mar. 2018, KEK物質構造科学研究所, J-PARCセンター

Pr1-2-20系の非磁性基底状態と多極子秩序の中性子散乱研究　　　　　　　　　　　　　　　
岩佐和晃; 鬼丸孝博; 高畠敏郎; 東中隆二; 青木勇二; 河村聖子; 中島健次
日本中性子科学会第17回年会, Dec. 2017

中性子回折による価数秩序物質YbPdの磁気構造の研究　　　　　　　　　　　　　　　
大山耕平; 光田暁弘; 大山研司; 松川健; 吉田幸彦; 星川晃範; 石垣徹; 岩佐和晃; 和田裕文
日本中性子科学会第17回年会, Dec. 2017

Resonant x-ray scattering study on hybridized orbital states in f-electron system　　　　　　　　　　　　　　　
H. Nakao; C. Tabata; K. Iwasa; and H. Amitsuka
International Workshop on Multipole Physics and Related Phenomena “J-Physics 2017”, Sep. 2017

Magnetic structure analysis of valence ordering compound YbPd　　　　　　　　　　　　　　　
K. Oyama; A. Mitsuda; K. Ohoyama; T. Matsukawa; Y. Yoshida; A. Hoshikawa; T. Ishigaki; K. Iwasa; H. Wada
International Workshop on Multipole Physics and Related Phenomena “J-Physics 2017”, Sep. 2017

Pr1-2-20系のf電子状態に関する中性子散乱研究　　　　　　　　　　　　　　　
岩佐和晃; 鬼丸孝博; 高畠敏郎; 東中隆二; 青木勇二; 河村聖子; 中島健次; Jean-Michel Mignot; Arsen Gukasov
日本物理学会2017年秋季大会, Sep. 2017

Sc置換LaCoO3における磁化と体積磁歪 スピン状態転移近傍に現れる励起子絶縁体の候補物質としての検討　　　　　　　　　　　　　　　
富安啓輔; 伊藤菜緒子; 岡崎竜二; 高橋佑生; 岩佐和晃; 青山拓也; 石原純夫; 大串研也
日本物理学会2017年秋季大会, Sep. 2017

価数秩序物質YbPdの磁気構造解析　　　　　　　　　　　　　　　
大山耕平; 光田暁弘; 大山研司; 松川健; 吉田幸彦; 星川晃範; 石垣徹; 岩佐和晃; 和田裕文
日本物理学会2017年秋季大会, Sep. 2017

Resonant x-ray scattering study on electronic hybridization in unconventional ordered phase of PrRu4P12　　　　　　　　　　　　　　　
H. Nakao; C. Tabata; K. Iwasa
The 28th International Conference on Low Temperature Physics LT28, Aug. 2017

Inelastic neutron scattering study on 4f-electron multipole system PrTr2X20 (Tr : transition metal, X : Al and Zn)　　　　　　　　　　　　　　　
Kazuaki Iwasa; Takahiro Onimaru; Toshiro Takabatake; Ryuji Higashinaka; Yuji Aoki; Seiko Ohira-Kawamura; Kenji Nakajima
International Conference on Neutron Scattering ICNS2017, Jul. 2017

Neutron-diffraction evidence for 4f-electron multipole ordering in PrIr2Zn20　　　　　　　　　　　　　　　
Kazuaki Iwasa; Keisuke T. Matsumoto; Takahiro Onimaru; Toshiro Takabatake; Jean-Michel Mignot; Arsen Gukasov
International Conference on Strongly Correlated Electron Systems SCES2017, Jul. 2017

中性子非弾性散乱によるPrNb2Al20の結晶場励起スペクトル　　　　　　　　　　　　　　　
岩佐和晃; 茨城大フロンティアセ; 東中隆二; 青木勇二; 河村聖子; 中島健次; PARCセ
日本物理学会第72回年次大会, Mar. 2017, 日本物理学会

Ce3Rh4Sn13のカイラル構造相における磁気状態の中性子散乱による研究　　　　　　　　　　　　　　　
巣山和哉; 岩佐和晃; 城大フロンティアセ; 富安啓輔; 河村聖子; 菊地龍弥; 古府麻衣子; 中島健次(J-PARCセ; F. Damay; J.-M. Mignot(LLB; P. Steffens(ILL; S. Raymo; CEA Grenoble
日本物理学会第72回年次大会, Mar. 2017, 日本物理学会

希釈三次元ハイゼンベルグ反強磁性体RbMnxMg1-xF3の磁性　　　　　　　　　　　　　　　
横山太紀; 浅野貴行; 稲垣祐次; 岩佐和晃; 城大フロンティアセ; 伊藤晋一(K; 菊池彦光
日本物理学会第72回年次大会, Mar. 2017, 日本物理学会

Ce3T4Sn13 (T = Co, Rh)におけるカイラル結晶構造と磁気励起　　　　　　　　　　　　　　　
岩佐和晃
日本中性子科学会第16回年会, Dec. 2016, 日本中性子科学会, [Invited]

三次元ハイゼンベルグ反強磁性体RbMnF3の磁気希釈効果　　　　　　　　　　　　　　　
横山太紀; 浅野貴行; 菊池彦光; 岩佐和晃; 茨城大フロンティアセ; 伊藤晋一(K
2016年度日本物理学会北陸支部定例学術講演会, Nov. 2016, 日本物理学会北陸支部

Neutron and x-ray scattering studies on electronic phase transitions in rare-earth metallic compounds　　　　　　　　　　　　　　　
Kazuaki Iwasa
The International Symposium of Quantum Beam Science at Ibaraki University, Nov. 2016, 茨城大学大学院理工学研究科量子線科学専攻, [Invited]

Ce3Co4Sn13におけるカイラル構造相転移と磁気励起　　　　　　　　　　　　　　　
岩佐和晃; 茨城大フロンティアセ; 大友優香; 巣山和哉; 富安啓輔; 河村聖子; 中島健次(J; PARCセ; Jean-Michel Mignot(Laboratoire Léon Brillouin
日本物理学会2016年秋季大会, Sep. 2016, 日本物理学会

非弾性中性子散乱によるCe0.7La0.3B6の磁気励起に関する研究　　　　　　　　　　　　　　　
小栗真哉; 貝木隆仁; 桑原慶太郎; 伊賀文俊; 岩佐和晃; 大フロンティア; 金子耕士(JAE; 椎名亮輔; 河村聖子; 中島健次(J-PAR; 横尾哲也; 伊藤晋一(K
日本物理学会2016年秋季大会, Sep. 2016, 日本物理学会

Anharmonic Atomic Vibrations and Structural Instability in Caged Lattice Systems　　　　　　　　　　　　　　　
Kazuaki Iwasa
Workshop for Quantum Beam Science held by Frontier Research Center for Applied Atomic Sciences, Ibaraki University under the sponsorship of J-PARC (KEK), Aug. 2016, 茨城大フロンティア応用原子科学研究センター、J-PARC (KEK)

Neutron scattering study on multipole degrees of freedom in Pr1-2-20 systems　　　　　　　　　　　　　　　
岩佐和晃
科学研究費補助金新学術領域 J-Physics 平成28年度領域全体会議(「トピカルセッション：“1-2-20 系”に関する研究の現状と課題Ⅰ」依頼講演), May 2016, [Invited]

Jun. 2024 - Aug. 2024
茨城大学

Apr. 2024 - Aug. 2024
茨城大学

Apr. 2001 - Present, The Japanese Society for Neutron Science

Jan. 1991 - Present, The Physical Society of Japan

〔Major achievements〕「アシンメトリが彩る量子物質の可視化・設計・創出」計画班分担（A01 量子ビームによるアシンメトリ量子物質のミクロ解析）
学術変革領域（A）
Apr. 2023 - Mar. 2028

Unveiling of the microscopic states of non-Fermi liquid behavior due to the magnetic two-channel Kondo effect.
Grant-in-Aid for Scientific Research (B)
Hiroshima University
Apr. 2024 - Mar. 2027

放射光光電子分光と物質開発を組み合わせた強相関希土類化合物の電子状態研究　　　　　　　　　　　　　　　
Apr. 2022 - Mar. 2024

〔Major achievements〕Superconductivity parity and magnetic frustration near quantum critical point of chiral symmetry structure
基盤研究（B）
Ibaraki University
Apr. 2020 - Mar. 2024

〔Major achievements〕Superconductivity parity and magnetic frustration near quantum critical point of chiral symmetry structure
茨城大学
Aug. 2020 - Mar. 2022

Examination of two-channel Kondo effect in diluted system　　　　　　　　　　　　　　　
基盤研究（B）
Apr. 2018 - Mar. 2022

電荷と磁気モーメントのドープによる高次多極子秩序に拮抗する自由度の活性化
新学術領域研究「3Ｄ活性サイト科学, A02 活性サイトの解析と次世代３Ｄ原子イメージング技術の開発(手法)」公募研究
Ibaraki University
Apr. 2017 - Mar. 2019

Study on strongly correlated electron systems by using high-order neutron magnetic,scattering processes　　　　　　　　　　　　　　　
基盤研究（A）
Nov. 2011 - Mar. 2016

Verification of gradon as a localized atomic vibrations in inhomogeneous matereials with mass gradient
Grant-in-Aid for Challenging Exploratory Research
Tohoku University
01 Apr. 2012 - 31 Mar. 2015

Study of Local Electronic State and the Hybridized Orbital Order under Magnetic Field and Pressure by Resonant Soft X-ray and Neutron Scattering
Grant-in-Aid for Scientific Research (S)
High Energy Accelerator Research Organization
11 May 2009 - 31 Mar. 2014

Study on the mechanism of metal-insulator transition in the pyrochlore iridates
Grant-in-Aid for Scientific Research (C)
Kyushu Institute of Technology
2011 - 2013

Spectroscopic studies on novel electronic phase due to large amplitude atomic oscillations
Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
Kobe University
2008 - 2012

Dynamical Jahn-Teller Effect due to The p-f Hybridization Effect in f-Electron Systems
Grant-in-Aid for Scientific Research (C)
Tohoku University
2007 - 2009

The Ordering and the Fluctuation of Electronic Degrees of Freedom Studied by Coherent X-rays and High Brilliance Neutrons
Grant-in-Aid for Scientific Research (S)
Tohoku University
2004 - 2008

強い混成効効を示す充填スクッテルダイト化合物の純良単結晶育成と物性評価
特定領域研究
首都大学東京
2003 - 2007

Pr充填スクッテルダイトにおける4f電子デュアリティーと多様な相転移
若手研究(B)
東北大学
2003 - 2004

Exotic Electronic Phenomena of the Low-Carrier System Ce-Monopnictides : From Localized to Itinerant
Grant-in-Aid for Scientific Research (B)
TOKYO METROPOLITAN UNIVERSITY
2002 - 2004

Study of noble electronic phases in the low-carrier strongly correlated systems under extreme conditions by diffraction techniques
Grant-in-Aid for Scientific Research (A)
TOKYO METROPOLITAN UNIVERSITY
1998 - 2001

偏極中性子散乱とX線回折による磁性f電子波動関数の研究
奨励研究(A)
東京都立大学
1999 - 2000

希薄キャリアー強相関係における特異な電子現象の極端条件下の研究
基盤研究(B)
東京都立大学
1999 - 1999

Study of exotic phenomena in the low-carrier strongly correlated systems
Grant-in-Aid for international Scientific Research
TOKYO METROPOLITAN UNIVERSITY
1997 - 1998

少数キャリアー強相関系Yb_4As_3の1次元特性の研究
重点領域研究
東京都立大学
1996 - 1996

少数キャリアー強相関電子系のスピン揺動の研究
重点領域研究
東京都立大学
1995 - 1995

Study of the formation of Magnetic Polaron Lattice in Low-Carrier strongly Correlated Systems
Grant-in-Aid for General Scientific Research (B)
1994 - 1995

KEK PF研究会「開発研究多機能ビームラインの建設と利用」
Panel chair etc
高エネルギー加速器研究機構物質構造科学研究所, 高エネルギー加速器研究機構, 05 Jan. 2023 - 06 Jan. 2023