2020年08月, Editor's Suggestion of Phys. Rev. B, Behavior of Sm in the boron-cage of Sm-doped RB6 (R=Yb,La) observed by multiple-wavelength neutron holography
学会誌・学術雑誌による顕彰

2005年09月, Papers of Editors' Choice, 日本物理学会
学会誌・学術雑誌による顕彰

2005年03月, 日本物理学会第10回論文賞, 日本物理学会

1999年11月, 原田研究奨励賞, (財)金属研究助成会
大山研司
出版社・新聞社・財団等の賞

Atomic Imaging of BaTiO3 by Multiple-Wavelength Neutron Holography
Kota Yamakawa; Hajime Nakada; Koji Kimura; Kenichi Oikawa; Masahide Harada; Yasuhiro Inamura; Kenji Ohoyama; Koichi Hayashi, The perovskite ferroelectric BaTiO3 has a high dielectric constant, and its ionic polarization has been studied in various ways. Atomic resolution holography is a method to obtain atomic arrangements around specific elements. It is also sensitive to atomic displacement, making it useful for evaluating the polarization at the atomic scale. In particular, neutron holography can be used to observe light elements such as O atoms, which are difficult to observe with X-rays. Thus, the displacement of anions and cations can be discussed using neutron holography. In this study, neutron holography experiments were performed on BaTiO3. We succeeded in observing clear oxygen atomic images around Ti. Based on the calculation of the image intensity as a function of atomic displacement, the displacement of the O atom relative to the Ti atom was 0.23 Å estimated from the observed image intensity of the O atom. Considering the atomic displacement parameter, the difference between the positions of Ti and O atoms in the polarization direction was estimated to be 0.16 Å. This study demonstrates that the observation of the oxygen atoms in BaTiO3 by neutron holography allowed us to evaluate the magnitude of the ionic polarization.
Journal of the Physical Society of Japan, 2024年10月15日

Development of instruments for imaging of local magnetic structure by magnetic neutron holography
Tomoya Kanno; Kenji Ohoyama; Hajime Nakada; Yuto Fukui; Kota Yamakawa; Shota Hoshi; Motoki Takano; Yodai Kobayashi; Yuka Tomimatsu; Shingo Takahashi; Takayuki Oku; Takuya Okudaira; Ryuju Kobayashi; Shusuke Takada; Masahide Harada; Kenichi Oikawa; Yasuhiro Inamura; Toetsu Shishido; Keisuke Sato; Koichi Hayashi, 責任著者, Elsevier BV
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2024年07月, ［査読有り］

Local Structures of Fe0.08Co0.92 Studied by X-ray Fluorescence Holography
Yuto Fukui; Tomoya Kanno; Kota Yamakawa; Hajime Nakada; Yodai Kobayashi; Keiko Widyanisa; Yuka Tomimatsu; Koji Kimura; Toetsu Shishido; Naohisa Happo; Kenji Ohoyama; Koichi Hayashi
e-Journal of Surface Science and Nanotechnology, 2023年07月, ［査読有り］

Determination of site occupancy of boron in 6H-SiC by multiple-wavelength neutron holography
Kouichi Hayashi; Maximilian Lederer; Yohei Fukumoto; Masashi Goto; Yuta Yamamoto; Naohisa Happo; Masahide Harada; Yasuhiro Inamura; Kenichi Oikawa; Kenji Ohoyama; and Peter Wellmann
Applied Physics Letters, 2022年03月28日, ［査読有り］

Chemical-Pressure-Induced Point Defects Enable Low Thermal Conductivity for Mg2Sn and Mg2Si Single Crystals
Wataru Saito; Kei Hayashi; Zhicheng Huang; Kazuya Sugimoto; Kenji Ohoyama; Naohisa Happo; Masahide Harada; Kenichi Oikawa; Yasuhiro Inamura; Kouichi Hayashi; Takamichi Miyazaki; Yuzuru Miyazaki, American Chemical Society (ACS)
ACS Applied Energy Materials, 2021年04月22日, ［査読有り］

Erratum: “Preparation, thermoelectric properties, and crystal structure of boron-doped Mg2Si single crystals” [AIP Advances 10, 035115 (2020)]
Kei Hayashi; Wataru Saito; Kazuya Sugimoto; Kenji Ohoyama; Kouichi Hayashi; Naohisa Happo; Masahide Harada; Kenichi Oikawa; Yasuhiro Inamura; Yuzuru Miyazaki, {AIP} Publishing
AIP Advances, 2021年02月01日

Behavior of Sm in the boron-cage of Sm-doped RB6 (R=Yb,La) observed by multiple-wavelength neutron holography
S. Uechi; K. Ohoyama; Y. Fukumoto; Y. Kanazawa; N. Happo; M. Harada; Y. Inamura; K. Oikawa; W. Matsuhra; F. Iga; A. K. R. Ang; K. Hayashi, 責任著者, American Physical Society (APS)
Phys. Rev. B, 2020年08月24日, ［査読有り］

Preparation, thermoelectric properties, and crystal structure of boron-doped Mg2Si single crystals
Kei Hayashi; Wataru Saito; Kazuya Sugimoto; Kenji Ohoyama; Kouichi Hayashi; Naohisa Happo; Masahide Harada; Kenichi Oikawa; Yasuhiro Inamura; Yuzuru Miyazaki, Mg2Si is a potential thermoelectric (TE) material that can directly convert waste energy into electricity. In expectation of improving its TE
performance by increasing electron carrier concentration, the element boron (B) is doped in Mg2Si single crystals (SCs). Their detailed crystal
structures are definitely determined by using white neutron holography and single-crystal x-ray diffraction (SC-XRD) measurements. The
white neutron holography measurement proves that the doped B atom successfully substitutes for the Mg site. The SC-XRD measurement
confirms the B-doping site and also reveals the presence of the defect of Si vacancy (VSi) in the B-doped Mg2Si SCs. The fraction of VSi
increases with increasing B-doping concentration. In the case of B-doped Mg2Si polycrystals (PCs), VSi is absent; this difference between the
SCs and PCs can be attributed to different preparation temperatures. Regarding TE properties, the electrical conductivity, σ, and the Seebeck
coefficient, S, decreases and increases, respectively, due to the decrease in the electron carrier concentration, contrary to the expectation. The
power factor of the B-doped Mg2Si SCs evaluated from σ and S does not increase but rather decreases by the B-doping. The tendencies of these
TE properties can be explained by considering that the donor effect of the B atom is canceled by the acceptor effect of VSi for the B-doped
Mg2Si SCs. This study demonstrates that the preparation condition of Mg2Si should be optimized to prevent the emergence of an unexpected
point defect., AIP Publishing
AIP Advances, 2020年03月13日, ［査読有り］

Tetragonality induced superconductivity in anti-ThCr2Si2-type RE2O2Bi (RE = rare earth) with Bi square net
Ryosuke Sei; Hideyuki Kawasoko; Kota Matsumoto; Masato Arimitsu; Kyohei Terakado; Daichi Oka; Shintaro Fukuda; Noriaki Kimura; Hidetaka Kasai; Eiji Nishibori; Kenji Ohoyama; Akinori Hoshikawa; Toru Ishigaki; Tetsuya Hasegawa and Tomoteru Fukumura, Royal Society of Chemistry ({RSC})
Dalton Transactions, 2020年02月11日, ［査読有り］

Investigation of magnetism and magnetic structure of anti-ThCr2Si2-type Tb2O2Bi by magnetization and neutron diffraction measurements　　　　　　　　　　　　　　　
Hideyuki Kawasoko; Kenji Ohoyama; Ryosuke Sei; Kota Matsumoto; Daichi Oka; Akinori Hoshikawa; Toru Ishigaki; Tomoteru Fukumura
AIP Advances,, 2019年10月01日, ［査読有り］

A case of multifunctional intermetallic compound: negative thermal expansion coupling with magnetocaloric effect in (Gd,Ho)(Co,Fe)2
Jinyu Hu; Kun Lin; Yili Cao; Rongjin Huang; Takeshi Matsukawa; Toru Ishigaki; Henry E. Fischer; Kenichi Kato; Takashi Honda; Kazutaka Ikeda; Toshiya Otomo; Kenji Ohoyama; Jinxia Deng; Jun Chen; Xianran Xing, Metallically functional materials with unique negative thermal expansion (NTE) or magnetocaloric effect (MCE) are promising in applications. Herein, we report the coexistence and coupling of NTE and MCE in (Gd,Ho)(Co,Fe)2 intermetallic compounds. Upon the incorporation of Gd and Fe, the coefficient of thermal expansion changed from strong negative in HoCo2 (HC, αV =-3.26 × 10-4 K-1) to moderate negative in HoCo1.92Fe0.08 (HCF, αV =-6.66 × 10-5 K-1) and to unusual zero in Gd0.3Ho0.7Co1.92Fe0.08 (GHCF, αV =-0.91 × 10-6 K-1); moreover, the corresponding magnetic entropy change-ΔSM reduced from the large value of 12.72 J kg-1 K-1 in HC to the small value of 2.98 J kg-1 K-1 in HCF and to the negligible value of 1.23 J kg-1 K-1 in GHCF under a field change of 2 T. Utilizing the temperature-dependent neutron powder diffraction and via magnetic measurements, we found that both NTE and MCE were governed by the same physical quantity, i.e., the reducing rate of magnetic moments at the rare earthsite upon heating, whereas MCE was further reinforced through an intermediate contribution from magnetovolume effect that gave rise to NTE. Thus, the present insight could be helpful for the future design of new multifunctional materials.
Inorg. Chem. Front.,, 2019年09月10日, ［査読有り］

Neutron Diffraction Studies on Valence Ordering Compound YbPd　　　　　　　　　　　　　　　
K. Oyama; M. Sugishima; K. Tanabe; A. Mitsuda; H. Wada; K. Ohoyama; T. Matsukawa; Y. Yoshida; A. Hoshikawa; T. Ishigaki; K. Iwasa
J. Phys. Soc. Jpn., 2018年10月10日, ［査読有り］

White neutron holography in pulsed neutron facilities
Kenji Ohoyama; Kouichi Hayashi, 筆頭著者
Physica Status Solidi B: Basic Solid State Physics, 2018年07月10日, ［査読有り］, ［招待有り］

Ready to roll? Time to launch POLANO
Tetsuya Yokoo; Shinichi Itoh; Naokatsu Kaneko; Masaki Fujita; Takashi Ino; Manabu Ohkawara; Kenji Ohoyama; Masataka Sakaguchi, POLANO is a newly constructed chopper spectrometer for polarization analysis in J-PARC. Its construction is almost complete, even though a few upgrades, the tuning, and R&
D of some devices and the beam line are still pending. After radiation assessments, POLANO has been approved as a proper neutron beam line and the beam commissioning process will commence soon. Our primary objective is to achieve higher-energy polarization analysis of inelastic scattering beyond a reactor-based neutron source up to 100 meV, with medium (reasonable) resolution. The other devices, such as spin filter polarizer and magnetic system are currently under development., American Institute of Physics Inc.
AIP Conference Proceedings, 2018年05月31日, ［査読有り］

Principle and reconstruction algorithm for atomic-resolution holography
Tomohiro Matsushita; Takayuki Muro; Fumihiko Matsui; Naohisa Happo; Shinya Hosokawa; Kenji Ohoyama; Ayana Sato-Tomita; Yuji C. Sasaki; Kouichi Hayashi, © 2018 The Physical Society of Japan. Atomic-resolution holography makes it possible to obtain the three-dimensional (3D) structure around a target atomic site. Translational symmetry of the atomic arrangement of the sample is not necessary, and the 3D atomic image can be measured when the local structure of the target atomic site is oriented. Therefore, 3D local atomic structures such as dopants and adsorbates are observable. Here, the atomic-resolution holography comprising photoelectron holography, X-ray fluorescence holography, neutron holography, and their inverse modes are treated. Although the measurement methods are different, they can be handled with a unified theory. The algorithm for reconstructing 3D atomic images from holograms plays an important role. Although Fourier transform-based methods have been proposed, they require the multiple-energy holograms. In addition, they cannot be directly applied to photoelectron holography because of the phase shift problem. We have developed methods based on the fitting method for reconstructing from single-energy and photoelectron holograms. The developed methods are applicable to all types of atomic-resolution holography.
Journal of the Physical Society of Japan, 2018年, ［査読有り］

Fe doping effects on the anomalous specific heat and XAFS oscillation in antiferromagnetic metal of Mn3Si
H. Hiraka; K. Ohoyama; M. Kosaka; D. Matsumura, AIP Publishing
AIP Advances., 2018年, ［査読有り］

Crystal structures, magnetic properties, and DFT calculation of B-site defected 12L-perovskites Ba2La2MW2O12 (M = Mn, Co, Ni, Zn)
Yoshihiro Doi; Makoto Wakeshima; Keitaro Tezuka; Yue Jin Shan; Kenji Ohoyama; Sanghyun Lee; Shuki Torii; Takashi Kamiyama; Yukio Hinatsu, The synthesis, crystal structures and magnetic properties of Ba2La2MW2O12 (M = Mn, Co, Ni, Zn) were investigated. They crystallize in the 12-layer polytype of the perovskite structure with a regular cation defect in the B-site. The results of neutron diffraction measurements reveal that they adopt a rhombohedral structure with a space group R - 3 and have a cation ordering between Ba and La ions in the A-site. In these compounds, the magnetic M ions form the 2D triangular lattice. From the results of magnetic measurements, the ferromagnetic ordering of M2+ ions for M = Co (T-C = 1.3 K) and Ni (6.2 K) and the paramagnetic behavior (T > 1.8 K) with an antiferromagnetic interaction for M = Mn are observed. From the DFT calculation, their band structures and magnetic interactions are discussed., IOP PUBLISHING LTD
JOURNAL OF PHYSICS-CONDENSED MATTER, 2017年09月, ［査読有り］

Multiple-wavelength neutron holography with pulsed neutrons
Kouichi Hayashi; Kenji Ohoyama; Naohisa Happo; Tomohiro Matsushita; Shinya Hosokawa; Masahide Harada; Yasuhiro Inamura; Hiroaki Nitani; Toetsu Shishido; Kunio Yubuta, Local structures around impurities in solids provide important information for understanding the mechanisms of material functions, because most of them are controlled by dopants. For this purpose, the x-ray absorption fine structure method, which provides radial distribution functions around specific elements, is most widely used. However, a similarmethod using neutron techniques has not yet been developed. If one can establish amethod of local structural analysis with neutrons, then a new frontier ofmaterials science can be explored owing to the specific nature of neutron scattering-that is, its high sensitivity to light elements andmagneticmoments. Multiple-wavelength neutron holography using the time-of-flight technique with pulsed neutrons has great potential to realize this. We demonstrated multiple-wavelength neutron holography using a Eu-doped CaF2 single crystal and obtained a clear three-dimensional atomic image around trivalent Eu substituted for divalent Ca, revealing an interesting feature of the local structure that allows it tomaintain charge neutrality. The newholography technique is expected to provide new information on local structures using the neutron technique., AMER ASSOC ADVANCEMENT SCIENCE
SCIENCE ADVANCES, 2017年08月, ［査読有り］

Development of a polarized He-3 neutron spin filter for POLANO at J-PARC
T. Ino; M. Ohkawara; K. Ohoyama; T. Yokoo; S. Itoh; Y. Nambu; M. Fujita; H. Kira; H. Hayashida; K. Hiroi; K. Sakai; T. Oku; K. Kakurai, We have developed a polarized He-3 neutron spin filter (NSF) for a new polarized neutron spectrometer, POLANO, at the Japan Proton Accelerator Research Complex (J-PARC). POLANO aims to utilize high energy neutrons polarized by a He-3 NSF and spin analyzed by an array of magnetic supermirrors for inelastic neutron scattering. The He-3 gas is continuously polarized in-situ by spin-exchange optical pumping to provide a highly and stably polarized neutron beam. The POLANO He-3 NSF is designed to polarize neutrons with energies as high as 200 meV and fit in a restricted space. It is equipped with adiabatic fast passage NMR that enables one to flip the He-3 spins, and consequently, the neutron spins., IOP PUBLISHING LTD
INTERNATIONAL CONFERENCE ON POLARISED NEUTRONS FOR CONDENSED MATTER INVESTIGATIONS (PNCMI 2016), 2017年, ［査読有り］

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.
Journal of Physics: Conference Series, 2016年05月11日, ［査読有り］

Conceptual design of a polarized ³He neutron spin filter for polarized neutron spectrometer POLANO at J-PARC
T. Ino; K. Ohoyama; T. Yokoo; S. Itoh; M. Ohkawara; H. Kira; H. Hayashida; K. Sakai; K. Hiroi; T. Oku; K. Kakurai; L. J. Chang, A 3He neutron spin filter (NSF) has been designed for a new polarized neutron chopper spectrometer called the Polarization Analysis Neutron Spectrometer with Correlation Method (POLANO) at the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex. It is designed to fit in a limited space on the spectrometer as an initial neutron beam polarizer and is polarized in situ by spin exchange optical pumping. This will be the first generation 3He NSF on POLANO, and a polarized neutron beam up to 100 meV with a diameter of 50 mm will be available for research on magnetism, hydrogen materials, and strongly correlated electron systems.
Journal of Physics: Conference Series, 2016年05月11日, ［査読有り］

20pPSB-30 価数秩序物質YbPdの粉末中性子回折
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, 一般社団法人日本物理学会
日本物理学会講演概要集, 2016年

Development of a 3He nuclear spin flip system on an in-situ SEOP 3He spin filter and demonstration for a neutron reflectometer and magnetic imaging technique
H. Hayashida; T. Oku; H. Kira; K. Sakai; K. Hiroi; T. Ino; T. Shinohara; T. Imagawa; M. Ohkawara; K. Ohoyama; K. Kakurai; M. Takeda; D. Yamazaki; K. Oikawa; M. Harada; N. Miyata; K. Akutsu; M. Mizusawa; J.D. Parker; Y. Matsumoto; S. Zhang; J. Suzuki; K. Soyama; K. Aizawa; M. Arai
J. Phys. Conf. Ser., 2016年, ［査読有り］

Local structure of room-temperature superionic Ag-GeSe3 glasses
J. R. Stellhorn; S. Hosokawa; Y. Kawakita; D. Gies; W. -C. Pilgrim; K. Hayashi; K. Ohoyama; N. Blanc; N. Boudet, Anomalous X-ray scattering experiments on amorphous Ag-0.5(GeSe3)(0.5) at the K absorption edges of each constituent element have been performed to investigate the local- and intermediate-range structure in this material. This method can provide insight into the structural properties enabling the effect of superionic conductivity in the amorphous phase. The experimental results were analyzed with reverse Monte Carlo modeling, providing the partial structure factors and the corresponding partial pair-distribution functions. A nanometer range phase separation tendency of the Ag atoms over a background of a GeSe4 tetrahedral network is observed, which may confirm the view of Ag conduction pathways forming in this phase. (C) 2015 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
JOURNAL OF NON-CRYSTALLINE SOLIDS, 2016年01月, ［査読有り］

Crystallographic, Electronic, and Magnetic Properties of Rock Salt Superstructure Sulfide Lu2CrS4 with Jahn-Teller Distortion
Tezuka Keitaro; Wakeshima Makoto; Nozawa Masataka; Oshikane Keita; Ohoyama Kenji; Shan Yue Jin; Imoto Hideo; Hinatsut Yukio
INORGANIC CHEMISTRY, 2015年10月19日, ［査読有り］

Development Status of the NMR System for the Polarized 3He Neutron Spin Filter (NSF) in the MLF at J-PARC
Kenji Sakai; Takayuki Oku; Hirotoshi Hayashida; Hiroshi Kira; Kosuke Hiroi; Takashi Ino; Kenji Ohoyama; Manabu Ohkawara; Kazuhisa Kakurai; Takenao Shinohara; Kenichi Oikawa; Masahide Harada; Kazuya Aizawa; Masatoshi Arai; Yoshifumi Sakaguchi; Jun-ichi Suzuki, Journal of the Physical Society of Japan
JPS Conf. Proc. 8, 036015, 2015年09月25日, ［査読有り］

Improvement of 3He nuclear polarization for neutron scattering　　　　　　　　　　　　　　　
Takashi Ino; Yasushi Arimoto; Hiroshi Kira; Hirotoshi Hayashida; Yoshifumi Sakaguchi; Manabu Ohkawara; Kenji Ohoyama; Kenji Sakai; Kosuke Hiroi; Takayuki Oku; Kazuhisa Kakurai
JPS Conf. Proc., 2015年, ［査読有り］

Demonstration study of small-angle polarized neutron scattering using polarized 3He neutron spin filter　　　　　　　　　　　　　　　
H. Kira; H. Hayashida; H. Iwase; K. Ohishi; J. Suzuki; T. Oku; K. Sakai; K. Hiroi; S. Takata; T. Ino; K. Ohoyama; M. Ohkawara; T. Shinohara; K. Kakurai; K. Aizawa; M. Arai
JPS Conf. Proc., 2015年, ［査読有り］

Polarized neutron spectrometer for inelastic experiments at J-PARC
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, 8295
EPJ Web of Conferences, 2015年01月, ［査読有り］

Neutron holography and diffuse scattering of palladium hydride
K. Hayashi; K. Ohoyama; S. Orimo; H. Takahashi; and K. Shibata, To extract a pure atomic-resolution hologram around hydrogen from a two-dimensional (2D) neutron intensity distribution around a single crystal, enhancement of the holographic signal and suppression of the diffuse scattering are important; sample cooling can achieve both. To estimate the performance of sample cooling in achieving these requirements, the angular anisotropy of the neutron intensities around a PdH0.78 single crystal was measured at 300 K and 100 K. In addition to the reduction in the diffuse scattering intensity, the pattern itself changed markedly upon sample cooling, thus indicating a significant modification of the hydrogen lattice dynamics. The reconstruction from a hologram, which was obtained by subtracting the diffuse scattering pattern, shows images of H and Pd nuclei as negative and positive peaks, respectively. In particular, such reconstruction at 100 K exhibits distinct H images at distant positions owing to the suppression of hydrogen motion. These features are important for the determination of hydrogen sites in various materials., AMER PHYSICAL SOC
Phys. Rev. B, 2015年01月, ［査読有り］

Polarized-neutron-diffraction study of the microscopic magnetic structure in α''−Fe16N2 nanoparticles
Polarized-neutron-diffraction study of; the microscopic magnetic structure in α”-F; nanoparticles; H. Hiraka; K. Ohoyama; Y. Ogata; T. Ogawa; R. Gallage; N. Kobayashi; M. Takahashi; B. Gillon; A. Gukasov; K. Yamada, Polarized-neutron-diffraction (PND) measurements were carried out using a pseudo-single-phase powder sample of ferromagnetic alpha ''-Fe16N2 nanoparticles. For the well-identified alpha ''-Fe16N2 phase, sizes of the magnetic moments at the three crystallographic Fe sites were determined in the absolute scale. The agreement between the magnetization value deduced from the present PND and that measured by a magnetometer (M-VSM) supports the hypothesis that M-VSM is primarily caused by the magnetization value in the target alpha ''-Fe16N2; thus there is no evidence for macroscopic giant saturation magnetization, at least for alpha ''-Fe16N2 nanoparticles. On the basis of the large magnetic moment size at one of the Fe sites, a possible coexisting state of localized spins and itinerant electron spins is inferred. Drawing a distinction between thin films and nanoparticles is currently necessary because of their divergent magnetic evolutions., AMER PHYSICAL SOC
Phys. Rev. B, 2014年10月, ［査読有り］

Novel Magnetic Chiral Structures and Unusual Temperature Hysteresis in the Metallic Helimagnet MnP
T. Yamazaki; Y. Tabata; T. Waki; T. J Sato; M. Matsuura; K. Ohoyama; M. Yokoyama; H. Nakamura, The Physical Society of Japan
J. Phys. Soc. Jpn., 2014年05月, ［査読有り］

Novel Magnetic Chiral Structures and Unusual Temperature Hysteresis in the Metallic Helimagnet MnP
Yamazaki Teruo; Tabata Yoshikazu; Waki Takeshi; Sato Taku J.; Matsuura Masato; Ohoyama Kenji; Yokoyama Makoto; Nakamura Hiroyuki, We have reinvestigated the magnetic properties of the classical metallic helimagnet MnP by magnetization and neutron scattering experiments. Our neutron scattering results indicate that the previously reported magnetic structure in the low-temperature (LT) helimagnetic phase (T < 47 K) should be modified to an alternately tilted helimagnetic structure produced by the Dzyaloshinsky-Moriya interaction. In the intermediate temperature (IT) range between the LT helimagnetic phase and the high-temperature (HT) ferromagnetic phase along the c-axis, 47 < T < 252 K, we have found a weak ferromagnetic behavior along the b-axis. Surprisingly, the IT weak ferromagnetic phase has two different states, namely, the large magnetization (LM) and small magnetization (SM) states. The SM state emerges with cooling from the paramagnetic phase above 292K via the HT ferromagnetic phase and LM state emerges with warming from the LT helimagnetic phase. The weak ferromagnetism along the b-axis and the unusual temperature hysteresis in the IT phase can be understood by assuming a spontaneous formation of the stripe structure consisting of alternately arranged HT ferromagnetic and LT helimagnetic domains., The Physical Society of Japan
Journal of the Physical Society of Japan, 2014年04月15日, ［査読有り］

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 and 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
J. Phys.: Conf. Ser., 2014年04月

Construction of Polarized Inelastic Neutron Spectrometer in J-PARC
T. Yokoo; K. Ohoyama; 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; M. Takeda; K. Kaneko; M. Hino; S. Muto, 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
Journal of Physics: Conference Series, 2014年04月

Development and demonstration of in-situ SEOP 3He spin filter system for neutron spin analyzer on the SHARAKU polarized neutron reflectometer at J-PARC
H. Hayashida; T. Oku; H. Kira; K. Sakai; M. Takeda; Y. Sakaguchi; T. Ino; T. Shinohara; K. Ohoyama; J. Suzuki; K. Kakurai; M. Mizusawa; N. Miyata; D. Yamazaki; R. Maruyama; K. Soyama; M. Arai, A new neutron reflectometer, SHARAKU, with a vertical sample-plane geometry was installed at beam line 17 at J-PARC Materials and Life Science Facility. Although a polarizing supermirror was previously installed as a neutron spin analyzer on SHARAKU, a He-3 spin filter is advantageous because it can cover a large solid angle. An in-situ SEOP He-3 spin filter system using a new compact laser unit has been developed for the analyzer. In this paper, we report a successful off-specular measurement with the new compact in-situ SEOP analyzer at SHARAKU., IOP PUBLISHING LTD
Journal of Physics: Conference Series,, 2014年04月

Diffusion Path and Conduction Mechanism of Protons in Hydroxyapatite,　　　　　　　　　　　　　　　
M. Yashima; N. Kubo; K. Omoto; H. Fujimori; K. Fujii; K. Ohoyama
J. Phys. Chem. C, 2014年02月

Development of ³He Neutron Spin Filter for the Application at an Intense Pulsed Neutron Source Facility
Takayuki Oku; Hiroshi Kira; Hirotoshi Hayashida; Kenji Sakai; Kosuke Hiroi; Takenao Shinohara; Takashi Ino; Manabu Ohkawara; Kenji Ohoyama; Shin-ichi Takata; Kazuki Ohishi; Hiroki Iwase; Noboru Miyata; Kazuhiro Akutsu; Yoshifumi Sakaguchi; Masayasu Takeda; Jun-ichi Suzuki; Kazuya Aizawa; Masatoshi Arai; Kazuhisa Kakurai, The Japanese Society for Neutron Science
hamon, 2014年

J-PARCでの可搬型偏極$^{3}$Heスピンフィルターの開発と磁気イメージングへの応用
酒井 健二; 奥 隆之; 林田 洋寿; 吉良 弘; 篠原 武尚; 及川 健一; 原田 正英; 加倉井 和久; 相澤 一也; 新井 正敏; 坂口 佳史; 鈴木 淳市; 猪野 隆; 大山 研司, 中性子偏極実験において測定領域を熱外中性子まで広げることは興味深い。その実現には、$^{3}$He自身の核スピンを反転することで、冷から熱外まで幅広いエネルギー領域の中性子のスピン偏極と反転が可能な偏極$^{3}$Heスピンフリッパー(PHSF)が重要な役割を果たす。現在、J-PARC/MLFでは「可搬型PHSF」の開発を進めている。この装置は、$^{3}$Heガスを封入したガラスセルを、$^{3}$Heスピン偏極を保持するための直径20cm,長さ30cmの小型ソレノイド内に設置する。さらに、ガラスセルをレーザー照射することで、光ポンピング法(SEOP)により$^{3}$Heを偏極した後に、ソレノイドごと中性子ビームラインに移動することで、可搬型PHSFとして利用する。われわれは、MLFの中性子ビームライン(BL10)で、PHSFの特性試験を行い、$^{3}$He核スピン反転前後の中性子透過率比の2次元分布測定から、本装置がPHSFとして十分機能することや、サンプルコイルの簡単な磁気イメージを測定できることを実証した。, IOP PUBLISHING LTD
Journal of Physics; Conference Series, 2014年, ［査読有り］

Development of portable polarized 3He spin flipper for polarized neutron experiment at J-PARC
K. Sakai; T. Oku; H. Hayashida; H. Kira; T. Shinohara; K. Oikawa; M. Harada; K. Kakurai; K. Aizawa; M. Arai; Y. Sakaguchi; J. Suzuki; T. Ino; K. Ohoyama
J. Phys.: Conf. Ser., 2014年, ［査読有り］

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),ビーム物理領域)
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; Lee C. H; Park J. G; Choi S, 一般社団法人日本物理学会
日本物理学会講演概要集, 2013年03月26日

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, The basic concept underlying the use of neutron polarisers and analysers in a polarised neutron spectrometer which will be constructed in J-PARC/MLF is discussed. The spectrometer, named POLANO, is a compact chopper spectrometer for polarisation analysis in the energy region up to E-i similar to 200 meV. In the first stage of this project, a He-3 spin filter polarised by the spin exchange optical pumping method will be used as the polariser. Based on the optimisations of the filter parameters, we confirm that the designed optimised He-3 spin filters will be feasible for use up to 80 meV., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2013年01月, ［査読有り］

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, 2013年01月

Precision magnetic field mapping for the He-3 neutron spin filter
Ino Takashi; Arimoto Yasushi; Kira Hiroshi; Sakaguchi Yoshifumi; Shinohara Takenao; Sakai Kenji; Oku Takayuki; Kakurai Kazuhisa; Ohoyama Kenji
9TH INTERNATIONAL CONFERENCE ON POLARISED NEUTRONS IN CONDENSED MATTER INVESTIGATIONS, 2013年, ［査読有り］

Physical properties of double perovskite-type barium neodymium osmate Ba2NdOsO6
Wakeshima Makoto; Hinatsu Yukio; Ohoyama Kenji
JOURNAL OF SOLID STATE CHEMISTRY, 2013年01月, ［査読有り］

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
J. Phys. Soc. Jpn., 2013年, ［査読有り］

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, 2012年12月14日, ［査読有り］

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, 2012年09月, ［査読有り］

(Sr _1-xBa _x)FeO ₂ (0.4 ≤ x ≤ 1): A new oxygen-deficient perovskite structure
T. Yamamoto; Y. Kobayashi; N. Hayashi; C. Tassel; T. Saito; S. Yamanaka; M. Takano; K. Ohoyama; Y. Shimakawa; K. Yoshimura; H. Kageyama, Topochemical reduction of (layered) perovskite iron oxides with metal hydrides has so far yielded stoichiometric compositions with ordered oxygen defects with iron solely in FeO4 square planar coordination. Using this method, we have successfully obtained a new oxygen-deficient perovskite, (Sr1-xBax)FeO2 (0.4 <= x <= 1.0), revealing that square planar coordination can coexist with other 3-6-fold coordination geometries. This BaFeO2 structure is analogous to the LaNiO2.5 structure in that one-dimensional octahedral chains are linked by planar units, but differs in that one of the octahedral chains contains a significant amount of oxygen vacancies and that all the iron ions are exclusively divalent in the high-spin state. Mossbauer spectroscopy demonstrates, despite the presence of partial oxygen occupations and structural disorders, that the planar-coordinate Fe2+ ions are bonded highly covalently, which accounts for the formation of the unique structure. At the same time, a rigid 3D Fe-O-Fe framework contributes to structural stabilization. Powder neutron diffraction measurements revealed a G-type magnetic order with a drastic decrease of the Neel temperature compared to that of SrFeO2, presumably due to the effect of oxygen disorder/defects. We also performed La substitution at the Ba site and found that the oxygen vacancies act as a flexible sink to accommodate heterovalent doping without changing the Fe oxidation and spin state, demonstrating the robustness of this new structure against cation substitution., AMER CHEMICAL SOC
Journal of the American Chemical Society, 2012年07月, ［査読有り］

Magnetic and Neutron Diffraction Study on Melilite-Type Oxides Sr2MGe2O7 (M = Mn, Co)
Endo Takashi; Doi Yoshihiro; Hinatsu Yukio; Ohoyama Kenji
INORGANIC CHEMISTRY, 2012年03月19日, ［査読有り］

Modified Cross-Correlation for Efficient White-Beam Inelastic Neutron Scattering Spectroscopy
K. Tomiyasu; M. Matsuura; H. Kimura; K. Iwasa; K. Ohoyama; T. Yokoo; S. Itoh; E. Kudoh; T. Sato; M. Fujita
Nuclear Instruments and Methods in Physics Research Section A, 2012年03月10日, ［査読有り］

Crystal Structure, Oxygen Deficiency, and Oxygen Diffusion Path of Perovskite-Type Lanthanum Cobaltites La0.4Ba0.6CoO3-delta and La0.6Sr0.4CoO3-delta
Yi-Ching Chen; Masatomo Yashima; Takashi Ohta; Kenji Ohoyama; Shinji Yamamoto, Crystal structures of perovskite-type lanthanum cobaltites, La0.4Ba0.6CoO3-delta and La0.6Sr0.4CoO3-delta, have been studied by in situ neutron powder diffractometry from 27 to 1258 C. La0.4Ba0.6CoO3-delta has a cubic Pm (3) over barm structure in the whole temperature range, while La0.6Sr0.4CoO3-delta exhibits a phase transition from hexagonal (R (3) over barc) to cubic (Pm (3) over barm) symmetry between 400 and 600 degrees C. Geometric information on oxygen diffusion is essential to understand the facile electrode reaction of perovskite-type cobaltites, but previous approaches have been limited to computational predictions. Here we provide long-awaited experimental evidence for a curved three-dimensional oxygen diffusion path in an ABO(3) mixed ionic-electronic conductor, La0.4Ba0.6CoO3-delta. The oxide ions diffuse in the (100) direction near the stable position, while the path is along (110) around the middle point of the path. The connected path as not visualized in La0.6Sr0.4CoO3-delta but in La0.4Ba0.6CoO3-delta, which indicates the higher oxygen diffusivity in La0.4Ba0.6CoO3-delta. The oxygen defect concentration, bottleneck size for oxygen diffusion, and oxygen atomic displacement parameter of La0.4Ba0.6CoO3-delta are higher than those of La0.6Sr0.4CoO3-delta, which are responsible for the higher oxygen diffusivity in La0.4Ba0.6CoO3-delta., AMER CHEMICAL SOC
JOURNAL OF PHYSICAL CHEMISTRY C, 2012年03月, ［査読有り］

Emergence of Magnetic Long-range Order in Frustrated Pyrochlore Nd2Ir2O7 with Metal-Insulator Transition
Tomiyasu Keisuke; Matsuhira Kazuyuki; Iwasa Kazuaki; Watahiki Masanori; Takagi Seishi; Wakeshima Makoto; Hinatsu Yukio; Yokoyama Makoto; Ohoyama Kenji; Yamada Kazuyoshi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2012年03月, ［査読有り］

Crystal structure refinement of Cu6O8YCl by powder neutron diffraction
Kenji Kawashima; Kazumasa Horigane; Kenji Ohoyama; Jun Akimitsu, We report the crystal structure parameters of clathrate-type copper-oxide Cu6O8YCl, which belongs to he Cu6O8MX (M = cation, X = anion) family, investigated by the powder neutron diffraction technique and the Rietveld method. The crystal structure of Cu6O8YCl was identified to be a cubic structure with the space group Fm (3) over barm. The Cl atom is located at the 4a, which is the center position of the Cu6O8 cage, and the Y atom occupies the 4b site in the cuboid space. The Y and Cl atoms have anomalously large atomic displacement parameters (U-iso) at room temperature which suggests that Y and Cl atoms respectively present in a cuboid and in a Cu6O8 cage exhibit intensive motion such as rattling, as recently observed for clathrate compounds., IOP PUBLISHING LTD
INTERNATIONAL CONFERENCE ON STRONGLY CORRELATED ELECTRON SYSTEMS (SCES 2011), 2012年, ［査読有り］

Magnetic impurity effect on charge and magnetic order in doped La1.5Ca0.5CoO4
K. Horigane; H. Hiraka; K. Tomiyasu; K. Ohoyama; D. Louca; K. Yamada, Neutron scattering experiments were performed on single crystals of magnetic impurity doped cobalt oxides La1.5Ca0.5CoO4 to characterize the charge and spin orders. We newly found contrasting impurity effects. Two types of magnetic peaks are observed at q=(0.5,0,L) with L=half-integer and integer in La1.5Ca0.5CoO4, while magnetic peak at L=half-integer (integer) was only observed in Mn (Fe)-substituted sample. Although Mn and Fe impurities degrade charge and magnetic order, Cr impurity stabilizes the ordering at x=0.5. Based on the crystal structural analysis of Cr doped sample, we found that the excess oxygen and change of octahedron around Co3+ were realized in Cr doped sample., IOP PUBLISHING LTD
5TH EUROPEAN CONFERENCE ON NEUTRON SCATTERING, 2012年, ［査読有り］

Development of a non-adiabatic two-coil spin flipper for a thermal polarised neutron diffractometer with a 3He spin filter
K. Ohoyama; K. Tsutsumi; T. Ino; H. Hiraka; Y. Yamaguchi; H. Kira; T. Oku; Y. Sakaguchi; Y. Arimoto; W. Zhang; H. Kimura; K. Iwasa; M. Takeda; J. Suzuki; K. Yamada; K. Kakurai
Nucl. Instr. and Methods in Phys. Res. A, 2012年, ［査読有り］

Development of polarized Xe gas target for neutron experiment at J-PARC
K. Sakai; T. Oku; T. Shinohara; H. Kira; M. Ooi; F. Maekawa; K. Kakurai; T. Ino; Y. Arimoto; H.M. Shimizu; Y. Sakaguchi; J. Suzuki; K. Ohoyama; L.J. Chang
J. Phys.: Conf. Ser., 2012年, ［査読有り］

High Field Neutron Diffraction Studies on Metamagnetic Transition of Multiferroic BiFeO3
Kenji Ohoyama; Seongsu Lee; Shunsuke Yoshii; Yasuo Narumi; Takayuki Morioka; Hiroyuki Nojiri; Gun Sang Jeon; Sang-Wook Cheong; Je-Geun Park, PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2011年12月, ［査読有り］

Magnetic correlations and the influence of atomic disorder in frustrated isosceles triangular lattice antiferromagnet CuMnO2
Noriki Terada; Yoshinori Tsuchiya; Hideaki Kitazawa; Toyotaka Osakabe; Naoto Metoki; Naoki Igawa; Kenji Ohoyama, We have studied the magnetic correlations of the isosceles triangular lattice antiferromagnet Cu1+xMn1-xO2 with x = 0.00 and 0.04, using the magnetic susceptibility, specific heat, elastic, and inelastic neutron-scattering experiments. Above T-N, the magnetic correlations in both samples are characterized by a two-dimensional (2D) short-range correlation, as indicated by the broad peak in the susceptibility and the asymmetric diffuse scattering observed in neutron diffraction experiments. Below T-N, the magnetic structures, with the propagation vectors Q = ((1/2) over bar 1/2 1/2) in x = 0.00 and Q = ((1/2) over bar 1/2 0) in x = 0.04, have been identified to be collinear magnetic structures with the magnetic moments almost parallel to the d(z)2 orbitals. Although the atomic disorder does not affect the direction and length of the magnetic moments in CuMnO2, the stacking sequence along the c direction is changed from antiferromagnetic to ferromagnetic. Considering the interlayer exchange interactions between isosceles triangular lattice layers, we find that the second-nearest-neighbor interlayer interaction plays an important role for the magnetic stacking along the c axis. The magnetic excitation below T-N is characterized by collective spin-wave excitation with an energy gap of 6 meV from the three-dimensional long-range magnetic order and by spin-liquid-like 2D excitation, as indicated by C(T) proportional to T-2 in CuMnO2., American Physical Society ({APS})
Physical Review B, 2011年08月

First-order-like antiferromagnetic transition and field-induced antiferroquadrupolar transition in terbium palladium bronze TbPd3S4
Eiichi Matsuoka; Hiroshi Shida; Takeshi Matsumura; Kenji Ohoyama; Hideya Onodera, Specific heat and magnetic susceptibility measurements were performed on single crystalline TbPd3S4, as well as neutron powder diffraction experiments in various magnetic fields. The sharp peak in the specific heat at the Neel temperature T-N = 2.55 K and the discontinuous decrease in the magnetic susceptibility at TN suggested that a first-order antiferromagnetic (AFM) transition was occurring. Field-induced phases were found above about 0.5 T. Since the phase boundary between the field-induced and paramagnetic phases in the B - T phase diagram is of the "re-entrant" type, the field-induced phase can be concluded to be antiferroquadrupolar (AFQ) ordering one. The appearance of a canted magnetic structure above 0.5 T supports the existence of field-induced AFQ ordering. In addition to a magnetic interaction, a quadrupolar or higher multipolar interaction is crucial for determining the magnetic ground state in TbPd3S4. The first-order-like AFM transition is caused by these multipolar interactions., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2011年07月, ［査読有り］

Research on glass cells for³He neutron spin filters
Y. Sakaguchi; H. Kira; T. Oku; T. Shinohara; J. Suzuki; K. Sakai; M. Nakamura; K. Suzuya; K. Aizawa; M. Arai; M. Takeda; S. Wakimoto; D. Yamazaki; S. Koizumi; Y. Endoh; L. J. Chang; L. J. Chang; L. J. Chang; Y. Arimoto; T. Ino; H. M. Shimizu; T. Kamiyama; K. Ohoyama; H. Hiraka; K. Tsutsumi; K. Yamada; K. Ohara; K. Kakurai, Glass cells play an important role in polarized3He neutron spin filters. To evaluate the scattering and absorption contribution from glass cells during neutron scattering experiments, we measured small-angle scattering and neutron transmission in GE180 and other glasses. The small-angle neutron scattering measurements revealed that the glasses used for3He spin filters have acceptably lower scattering: dΣ(Q)/dΩ=47×10-4cm-1at Q=0.030.12 Å-1. The transmission measurement was performed at J-PARC. Neutron transmission of about 92% through empty GE180 cells was observed over a wide wavelength range 0.0147.0 Å. To pursue the possibility of being a structural influence on3He spin relaxation in GE180 glass cells, we performed precise X-ray diffraction measurement using synchrotron radiation at SPring-8. From these measurements, a structural difference was observed among GE180 glasses with different thermal treatments. © 2010 Elsevier B.V. All rights reserved.
Physica B: Condensed Matter, 2011年06月, ［査読有り］

The Fermi Chopper Spectrometer 4SEASONS at J-PARC
Ryoichi Kajimoto; Mitsutaka Nakamura; Yasuhiro Inamura; Fumio Mizuno; Kenji Nakajima; Seiko Ohira-Kawamura; Tetsuya Yokoo; Takeshi Nakatani; Ryuji Maruyama; Kazuhiko Soyama; Kaoru Shibata; Kentaro Suzuya; Setsuo Sato; Kazuya Aizawa; Masatoshi Arai; Shuichi Wakimoto; Motoyuki Ishikado; Shin-ichi Shamoto; Masaki Fujita; Haruhiro Hiraka; Kenji Ohoyama; Kazuyoshi Yamada; Chul-Ho Lee
J Phys. Soc. Jpn, 2011年05月13日, ［査読有り］

Large Topological Hall Effect in a Short-Period Helimagnet MnGe
N. Kanazawa; Y. Onose; T. Arima; D. Okuyama; K. Ohoyama; S. Wakimoto; K. Kakurai; S. Ishiwata; Y. Tokura, We have observed an unconventional, likely topological, Hall effect over a wide temperature region in the magnetization process of a chiral-lattice helimagnet MnGe. The magnitude of the topological Hall resistivity is nearly temperature-independent below 70 K, which reflects the real-space fictitious magnetic field proportional to a geometric quantity (scalar spin chirality) of the underlying spin texture. From the neutron diffraction study, it is anticipated that a relatively short-period (3-6 nm) noncoplanar spin structure is stabilized from the proper screw state in a magnetic field to produce the largest topological Hall response among the B20-type (FeSi-type) chiral magnets., AMER PHYSICAL SOC
PHYSICAL REVIEW LETTERS, 2011年04月, ［査読有り］

Spontaneous strain in ferroquadrupolar phase of TmAu2
M. Kosaka; Y. Shida; A. Imanari; S. Katano; K. Ohoyama; H. Onodera, We present the results of a study of the spontaneous strain accompanied by a ferroquadrupolar ordering in TmAu2. The strain has been investigated by means of thermal expansion, magnetostriction, and neutron diffraction measurements on a single crystalline TmAu2. In the ferroquadrupolar ordered phase, the strain shows a strong enhancement by applying magnetic field. This implies that structural orthorhombic domains caused by the ferroquadrupolar ordering are transformed into a single-domain structure by a magnetic field., IOP PUBLISHING LTD
INTERNATIONAL CONFERENCE ON STRONGLY CORRELATED ELECTRON SYSTEMS (SCES 2010), 2011年, ［査読有り］

Importance of neutron scattering for materials science: Expectations on magnetic holography
Kenji Ohoyama; Kouichi Hayashi; Haruhiro Hiraka, The neutron scattering technique is an indispensable probe for structural investigations of materials, particularly, for observations of light atoms and magnetic moments. Using the IMR neutron powder diffractometer HERMES, which can observe scattering patterns in wide Q rage at once, we have succeeded in performing neutron holography experiments in a Pd-H compound. Holography will become a quite important technique for local structure investigations of materials. Moreover, as the next stage, magnetic holography with polarized neutrons must be promising. © 2011 The Surface Science Society of Japan.
e-Journal of Surface Science and Nanotechnology, 2011年, ［査読有り］

Applications of ³He neutron spin filters on the small-angle neutron scattering spectrometer SANS-J-II
Y. Sakaguchi; H. Kira; T. Oku; T. Shinohara; J. Suzuki; K. Sakai; M. Nakamura; K. Aizawa; M. Arai; Y. Noda; S. Koizumi; M. Takeda; Y. Endoh; L. J. Chang; Y. Arimoto; T. Ino; H. M. Shimizu; T. Kamiyama; K. Ohoyama; H. Hiraka; K. Tsutsumi; K. Yamada; K. Kakurai, A polarized 3He neutron spin filter has been applied to polarization analysis on the small-angle neutron scattering spectrometer SANS-J-II at JRR-3. Measurements were taken on silver behenate, which has several coherent peaks in the small-angle region with a background of spin incoherent hydrogen scattering. Here we demonstrate that the coherent and spin incoherent scattering were successfully separated by the polarization analysis using the 3He spin filter on the instrument. © Published under licence by IOP Publishing Ltd., IOP PUBLISHING LTD
Journal of Physics: Conference Series, 2011年, ［査読有り］

Structure of glasses for ³He neutron spin filter cells
Y. Sakaguchi; H. Kira; T. Oku; T. Shinohara; J. Suzuki; K. Sakai; M. Nakamura; K. Suzuya; K. Aizawa; M. Arai; M. Takeda; Y. Endoh; L. J. Chang; Y. Arimoto; T. Ino; H. M. Shimizu; T. Kamiyama; K. Ohoyama; H. Hiraka; K. Tsutsumi; K. Yamada; K. Ohara; K. Kakurai, In spin-exchange optical pumping, there is unknown excess relaxation, called the X-factor, that limits attainable 3He polarization. It is known that the X-factor depends on the glass containers. Hence, it is expected that there are cell-to-cell variations in microscopic structure among the cells and that these variations affect the attainable 3He polarization. However, microscopic structure of the glasses for 3He neutron spin filters has not been clarified yet. In this paper, we have performed precise X-ray diffraction measurements for the glasses at SPring-8 using synchrotron radiation. The structural differences are observed between several types of glasses, and also, between the GE180 glass pieces with different thermal treatment. Based on the results, the structural influence on the performance of 3He neutron spin filters is discussed. © Published under licence by IOP Publishing Ltd., IOP PUBLISHING LTD
Journal of Physics: Conference Series, 2011年, ［査読有り］

Development and test of SEOP neutron spin filter in Japan
H. Kira; Y. Sakaguchi; T. Oku; J. Suzuki; M. Nakamura; M. Arai; K. Kakurai; Y. Endoh; Y. Arimoto; T. Ino; H.M. Shimizu; T. Kamiyama; K. Tsutsumi; K. Ohoyama; H. Hiraka; K. Yamada; L.-J. Chang
Physica B, 2011年, ［査読有り］

Orthogonal Spin Arrangement in Quasi-Two-Dimensional La2Co2O3Se2
Fuwa Yayoi; Endo Takashi; Wakeshima Makoto; Hinatsu Yukio; Ohoyama Kenji
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2010年12月29日, ［査読有り］

Multimode hydriding/dehydriding reactions of CaPd　　　　　　　　　　　　　　　
Kazutaka Ikeda; Noriki Okuda; Kenji Ohoyama; Hai-Wen Li; Hiroyuki T. Takeshita; Toshiya Otomo; Shin-ichi Orimo
CHEMICAL COMMUNICATIONS, 2010年10月06日

Antiferromagnetic Alignment of Magnetic Dipolar Moments Observed by Neutron Powder Diffraction in Rare-Earth Palladium Bronze PrPd3S4
Matsuoka Eiichi; Usui Daichi; Sasaki Yuta; 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 $T_{\text{M } } = 1.56$ 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 Th 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 $T_{\text{M } }$ 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 Society of Japan
J Phys Soc Jpn, 2010年06月15日

Hot pressing of Ge crystals toward a reflection-plane-selective neutron monochromator
Y. Miyake; H. Hiraka; K. Ohoyama; Y. Yamaguchi; K. Yamada, We determined a hot-pressing condition of temperature and pressure to fabricate a Ge-crystal monochromator. After hot pressing under the optimal condition, a reflected beam by the Ge crystals shows an appropriate peak width (∼0.3° in FWHM) and an enhanced peak reflectivity (∼40%). The feasibility of reflection-plane-selective monochromator, which consists of Ge crystals, is confirmed by magnetic powder neutron diffraction in the high-Q survey mode as well as in the fine Q-resolution mode. © 2010 IOP Publishing Ltd., Institute of Physics Publishing
Journal of Physics: Conference Series, 2010年

Non-Fermi-Liquid Behavior on an Iron-Based Itinerant Electron Magnet Fe3Mo3N
Waki Takeshi; Terazawa Shinsuke; Tabata Yoshikazu; Oba Fumiyasu; Michioka Chishiro; Yoshimura Kazuyoshi; Ikeda Shugo; Kobayashi Hisao; Ohoyama Kenji; Nakamura Hiroyuki
Journal of the Physical Society of Japan, 2010年, ［査読有り］

Neutron Diffraction Study on the Multiple Magnetization Plateaus in TbB₄ under Pulsed High Magnetic Field
S. Yoshii; K. Ohoyama; K. Kurosawa; H. Nojiri; M. Matsuda; P. Frings; F. Duc; B. Vignolle; G. L. J; A. Rikken; L. -P. Regnault; S. Michimura; F. Iga
Phys. Rev. Lett., 2009年08月14日, ［査読有り］

Synchrotron radiation powder X-ray and neutron diffraction studies on novel Y₃Al₂ hydrides
T. Sato; K. Ikeda; K. Ohoyama; N. Watanabe; S. Orimo
Journal of Alloys and Compounds, 2009年07月, ［査読有り］

Magnetic Phase Diagrams of Dy0.8Gd0.2B2C2 with the Antiferroquadrupolar Ordering in the Antiferromagnetic Phase
Eiichi Matsuoka; Shoei Ogushi; Yuta Sasaki; Masato Sakata; Kenji Ohoyama; Hideya Onodera, Gd Substitution for Dy in DyB2C2 that undergoes an antiferroquadrupolar (AFQ) ordering at T-Q = 24.7 K and an antiferromagnetic (AFM) one at T-N = 15.3 K enhances the AFM interaction and weakens the AFQ interaction. In Dy0.8Cd0.2B2C2, the AFQ transition occurs at T-Q = 17.6 K below the AFM one at T-N = 19.0 K. However, the strong competition between the AFQ and AFM interactions supresses the development of the AFQ order parameter below TQ and causes an anomalous behavior in field-induced transitions. The magnetic phase diagrams of Dy0.8Gd0.2C2B2 drawn from the experimental results of specific heat and magnetization have anomalous phase boundaries originating from this competition., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2009年03月, ［査読有り］

Complex Magnetic Structures of a Shastry-Sutherland Lattice TmB4 Studied by Powder Neutron Diffraction Analysis
S. Michimura; A. Shigekawa; F. Iga; T. Takabatake; K. Ohoyama, Powder neutron diffraction analysis was performed on (TmB1)-B-11, which undergoes successive transitions at T-N1 = 11.7K, T* = 11 K, aid T-N2 = 10K. An incommensurate structure with two propagation vectors, k(2) [1 +/- k' +/- k" +/- k", 0] and k(2)' = [1 +/- k' +/- 3k", +/- k", 0] (k' = 0.1226 and k" similar or equal to 0.012). is suggested for phase II (T-3 <= T <= T-N1). Phase III (T-N2 <= T <= T-(sic)) is described by one propagation vector, k(3) = [1 +/- k',0,0]. The propagation vector for phase IV (T <= T-N2) further changes to a commensurate one characterized by k(4) = [100]. Four Tm moments in the c-plane order in a (+-+-) type, where + and - mean the directions of the moments parallel and antiparallel to the c-direction, respectively. The diffuse scattering intensity around the (100) magnetic reflection remains above T-N2 up to 20 K.
Journal of the Physical Society of Japan, 2009年01月26日, ［査読有り］

CaFeO2: A New Type of Layered Structure with Iron in a Distorted Square Planar Coordination
Cedric Tassel; Jose Miguel Pruneda; Naoaki Hayashi; Takashi Watanabe; Atsushi Kitada; Yoshihiro Tsujimoto; Hiroshi Kageyama; Kazuyoshi Yoshimura; Mikio Takano; Masakazu Nishi; Kenji Ohoyama; Masaichiro Mizumaki; Naomi Kawamura; Jorge Iniguez; Enric Canadell, CaFeO2, a material exhibiting an unprecedented layered structure containing 3d(6) iron in a high-spin distorted square-planar coordination, is reported. The new phase, obtained through a low-temperature reduction procedure using calcium hydride, has been characterized through powder neutron diffraction, synchrotron X-ray diffraction, Mossbauer spectroscopy, XAS experiments as well as first-principles DFT calculations. The XAS spectra near the Fe-K edge for the whole solid solution (Sr1-xCax)FeO2 supports that iron is in a square-planar coordination for 0 <= x <= 0.8 but clearly suggests a change of coordination for x = 1. The new structure contains infinite FeO2 layers in which the FeO4 units unprecedentedly distort from square-planar toward tetrahedra and rotate along the c-axis, in marked contrast to the well-studied and accepted concept that octahedral rotation in perovskite oxides occurs but the octahedral shape is kept almost regular. The new phase exhibits high-spin configuration and G-type antiferromagnetic ordering as in SrFeO2. However, the distortion of the FeO2 layers leads to only a slight decrease of the Neel temperature with respect to SrFeO2. First-principles DFT calculations provide a clear rationalization of the structural and physical observations for CaFeO2 and highlight how the nature of the cation influences the structural details of the AFeO(2) family of compounds (A = Ca, Sr, Ba). On the basis of these calculations the driving force for the distortion of the FeO2 layers in CaFeO2 is discussed., AMER CHEMICAL SOC
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2009年01月, ［査読有り］

Crystal Structures and Magnetic Properties of Two—dimensional Antiferromagnets Co1-xZnxTeMnO6
Y. Doi; R. Suzuki; Y. Hinatsu; K. Ohoyama
J. Solid State Chem., 2009年

Magnetic and Neutron Diffraction Study on Quaternary Oxides MTeMoO6 (M = Mn and Zn)
Y. Doi; R. Suzuki; Y. Hinatsu; K. Ohoyama
J. Phys.: Condens. Matter, 2009年

Structural and Magnetic Properties of the Quaternary Oxides Ba6Ln2Fe4O15 (Ln = Pr and Nd)
K. Abe; Y. Doi; Y. Hinatsu; K. Ohoyama
J. Solid State Chem., 2009年

Development of a compact on-beam SEOP neutron spin filter
T. Ino; M. Nakamura; T. Oku; T. Shinohara; J. Suzuki; K. Ohoyama; H. Hiraka
Physica B, 2009年, ［査読有り］

Field-Induced Magnetic Structures in Antiferroquadrupolar Ordering Compound DyB2C2
Kenji Ohoyama; Kentaro Indoh; Hiroki Yamauchi; Aya Tobo; Eiichi Matsuoka; Masugu Sato; Susumu Katano; Hideya Onodera, Neutron scattering experiments were performed on the single-crystal line DyB2C2 under magnetic fields in order to elucidate the magnetic structures of field-induced phases. The measurements in the a*-c* reciprocal lattice plane under the magnetic fields along the [010] direction resulted in finding a new magnetic reflection of 1 0 3/4 in a field-induced phase (phase II") in addition to the magnetic reflections that are common to those in the phase under a zero magnetic field (phase III). The magnetic unit cell in phase II" has dimensions of axax4c. where all the Dy magnetic moments on the AFQ structure have advantageous directions to the magnetic field, and their AFQ couplings with the neighbouring moments along the c-axis are partly broken. This, PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2008年11月, ［査読有り］

Simultaneous Occurrence of an Antiferroquadrupolar and a Ferromagnetic Transitions in Rare-Earth Palladium Bronze CePd3S4
Eiichi Matsuoka; Daichi Usui; Yuta Sasaki; Hironori Nakao; Hiroshi Shida; Kenji Ohoyama; Hideya Onodera, Neutron powder diffraction experiments have been performed on CePd3S4 as well as measurements of magnetic and transport properties on a single-crystal line sample. Magnetic susceptibility increases markedly below T-C = 6.3 K and a spontaneous Magnetization appears below T-C. The logarithmic temperature dependence of electrical resistivity implies that CePd3S4 is classified into a Kondo-lattice compound whose Kondo temperature is comparable to T-C. Magnetic susceptibility is analyzed satisfactorily with a crystalline electric field model that the 4f ground state of Ce3+ is the Gamma(8) quartet with the excited Gamma(7) doublet located at 630 K. The magnetic structure of CePd3S4 was determined to be a canted structure with a canting angle of 51 degrees. Such a canted structure is a result of the ferromagnetic (FM) ordering and simultaneous [100]-type antiferroquadrupolar (AFQ) ordering at T-C. The smaller magnetization values and an unexpectedly high T-C can be explained by the simultaneous occurrence of AFQ and FM order., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2008年11月, ［査読有り］

Experimental visualization of lithium diffusion in LixFePO4
Shin-ichi Nishimura; Genki Kobayashi; Kenji Ohoyama; Ryoji Kanno; Masatomo Yashima; Atsuo Yamada, Chemical energy storage using batteries will become increasingly important for future environmentally friendly ('green') societies. The lithium-ion battery is the most advanced energy storage system, but its application has been limited to portable electronics devices owing to cost and safety issues(1). State-of-the-art LiFePO4 technology as a new cathode material with surprisingly high charge-discharge rate capability has opened the door for large-scale application of lithium-ion batteries such as in plug-in hybrid vehicles(2-5). The scientific community has raised the important question of why a facile redox reaction is possible in the insulating material(6-14). Geometric information on lithium diffusion is essential to understand the facile electrode reaction of LixFePO4 (0 < x < 1), but previous approaches have been limited to computational predictions(15,16). Here, we provide long-awaited experimental evidence for a curved one-dimensional chain for lithium motion. By combining high-temperature powder neutron diffraction and the maximum entropy method, lithium distribution along the [010] direction was clearly visualized., NATURE PUBLISHING GROUP
NATURE MATERIALS, 2008年09月, ［査読有り］

Diffusion Path of Oxide Ions in an Apatite-Type Ionic Conductor La-9.69(Si5.70Mg0.30)O-26.24
Roushown Ali; Masatomo Yashima; Yoshitaka Matsushita; Hideki Yoshioka; Kenji Ohoyama; Fujio Izumi, Densities of coherent-scattering lengths in oxide-ion conductor La-9.69(Si5.70Mg0.30)O-26.24 with an apatite-type structure (space group P6(3)/m) have been determined by a whole-pattern fitting approach based on the maximum-entropy method (MEM) using neutron powder diffraction data measured at 25 and 1558 degrees C. The Rietveld refinement Suggested an interstitial oxygen (O5) atom site (12i; x, y, z; x approximate to 0, y approximate to 0.22, z approximate to 0.65) at the periphery of the hexagonal axis. The oxide ions located at 2a (O4) and 12i (O3) sites are largely distributed parallel and perpendicular to the c axis, respectively. The densities of coherent-scattering lengths derived from the MEM analysis revealed that the 04 oxide ions located at the 2a site (0, 0, 1/4) diffuse to nearest-neighbor 2a sites along the [001] direction. This [001] diffusion path is linearly linked with that of neighboring unit cell, which forms a long-range, one-dimensional oxide-ion diffusion pathway extending along the c axis of the hexagonal P6(3)/m framework. The probability density of the O3 ion is connected with that of the equivalent O3 of the same tetrahedron through the interstitial O5 ion, indicating migration of the ions along a curved line connecting O3-O5-O3 atoms. This migration path is nonlinear (U-shaped) and perpendicular to the c axis. The densities of the two kinds of oxide ions (O4 and O3) migrating parallel and perpendicular to the c axis, respectively, connected with each other through the densities of interstitial oxide ion (O5). The results suggest that the O4 ion migrates via vacancy mechanism with a direct linear path along the c axis, while the O3 ion migration perpendicular to the c axis involves an interstitial mechanism., AMER CHEMICAL SOC
CHEMISTRY OF MATERIALS, 2008年08月, ［査読有り］

Neutron diffraction and isotropic volume expansion caused by deuterium absorption into La(Fe$$_0.88$$Si$$_0.12$$)$$₁₃$$
S. Fujieda; A. Fujita; K. Fukamichi; Y. Yamaguchi; K. Ohoyama, The crystal structures and magnetic properties of La(Fe 0:88Si0:12)13D1:5 and La(Fe 0:88Si0:12)13H1:6 have been investigated. The powder neutron diffraction declared that the compound La(Fe0:88Si0:12)13D1:5 has a cubic NaZn13-type structure of the Fm33c space group in analogy with La(Fe0:88Si0:12)13. The deuterium atoms in the compound La(Fe0:88Si0:12)13D1:5 occupy the interstitial 24d site surrounded by two La atoms and four icosahedral clusters. The x-ray diffraction data of La(Fe0:88Si 0:12)13H1:6 are also consistently explained by the same site of hydrogen atom. The deuterium or hydrogen absorption brings out a notable increase of the Curie temperature TC. The neutron diffraction of the compound La(Fe0:88Si0:12) 13D1:5 shows that the magnetic structure is ferromagnetic and the average magnetic moment per Fe is about 2.2 μB, almost the same as that of La(Fe0:88Si0:12)13. Such behaviors can be explained as characteristic magnetovolume effects in itinerant-electron metamagnets. That is, when the hydrogen or deuterium atom at the 24d site causes the isotropic volume expansion, the magnetic free energy curve with a double minimum structure renormalized by spin fluctuations induces a marked increase of TC without a pronounced increase of the magnetic moment. ©2008 The Physical Society of Japan.
J. Phys. Soc. Jpn, 2008年07月01日

Giant uniaxial anisotropy in the magnetic and transport properties of CePd5Al2
Onimaru, Takahiro; Inoue; Yukihiro F; Shigetoh, Keisuke; Umeo, Kazunori; Kubo, Hirokazu; Ribeiro, Raquel A; Ishida, Akihiro; Avila, Marcos A; Ohoyama, Kenji; Sera; Masafumi e, Electrical resistivity p, magnetic susceptibility chi magnetization M, and specific heat measurements are reported on a singlecrystalline sample of CePd5Al2, showing successive antiferromagnetic orderings at T-N1 = 4.1 K and T-N2 = 2.9 K. The temperature dependence of rho shows a Kondo metal behavior with large anisotropy, rho(c)/rho(a) = 3.2 at 20 K, and opening of a superzone gap along the tetragonal c-direction below T-N1. Both T-N1 and T-N2 gradually increase with applying pressure up to 2.5 GPa. The data of chi(T) and M(B) in the paramagnetic state were analyzed using a crystalline electric field (CEF) model. It led to a Kramers doublet ground state with wave functions consisting primarily of vertical bar+/- 5/2 >, whose energy level is isolated from the excited states by 230 and 300 K. This CEF effect gives rise to the large anisotropy in the paramagnetic state. In the ordered state, the uniaxial magnetic anisotropy is manifested as M-c/M-a = 20 in B = 5 T and at 1.9 K, and chi(c)/chi(a) = 25 in B = 0.1 T and at 4 K. In powder neutron diffraction experiments, magnetic reflections were observed owing to the antiferromagnetic ordered states below T-N1, whereas no additional ref, PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2008年07月, ［査読有り］

Neutron holography measurement using multi array detector
K. Hayashi; K. Ohoyama; S. Orimo; Y. Nakamori; H. Takahashi; K. Shibata
Japanese Journal of Applied Physics, 2008年04月, ［査読有り］

Experimental and computational studies on solvent-free rare-earth metal borohydrides RE(BH₄)₃ (RE = Y, Dy, and Gd)
T. Sato; K. Miwa; Y. Nakamori; K. Ohoyama; H.-W. Li; T. Noritake; M. Aoki; S. Towata; S. Orimo
Phys. Rev. B, 2008年, ［査読有り］

Search of Long-Range Magnetic Ordering in Superconducting Five-Layered Cuprate
C.H. Lee; A. Iyo; K. Kihou; H. Kito; H. Hiraka; K. Ohoyama; K. Yamada
J. Phys. Soc. Jpn., 2008年, ［査読有り］

Synthesis, Crystal Structures and Magnetic Properties of New 12L-Perovskites Ba4LnRu3O12 (Ln = Lanthanides)
Y. Shimoda; Y. Doi; Y. Hinatsu; K. Ohoyama
Chem. Mater., 2008年

On the magnetic symmetry of the low temperature phase of ZnCr2O4
Kagomiya, Isao; Hata, Yoshiaki; Eto, Daisuke; Yanagihara, Hideto; Kita, Eiji; Nakajima, Kenji; Kakurai, Kazuhisa; Nishi, Masakazu; Ohoyama, Kenji, PHYSICAL SOCIETY JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2007年06月, ［査読有り］

Magnetic properties of LaMnO_3+δ nanocrystals in MCM-41mesoporous silica
H. Kira; H. Tamura; Y. Ando; M. Onodera; H. Nakao; Y. Murakami; K.Tsuda; K. Ohoyama; S. Yamazaki; T. Tajiri; H. Deguchi, The LaMnO3+delta crystal has successfully been synthesized in a mesoporous silica MCM- 41 by an improvement in the impregnation method. X- ray diffraction measurement has revealed that the crystal has a rhombohedral structure and the average particle size is about 9.5 nm. Ferromagnetic behavior with a hysteresis of the magnetization curve was observed below T 280 K; however, the magnetization is not saturated up to H 7T at T 5K. These results suggest that ferromagnetic and antiferromagnetic regions coexist in the sample. (c) 2006 Elsevier B. V. All rights reserved., ELSEVIER SCIENCE BV
Journal of Magnetism and Magnetic Materials, 2007年03月, ［査読有り］

[要修正]Inelastic neutron scattering measurements in a quadrupolar ordering compound YbSb
A. Oyamada; K. Kuwahara; K. Ohoyama; K. Iwasa; M. Kohgi; S. Maegawa
Journal of Magnetism and Magnetic Materials, 2007年03月, ［査読有り］

Neutron diffraction under 30 T pulsed magnetic fields
K. Ohoyama; N. Katoh; H. Nojiri; Y.H. Matsuda; H. Hiraka; K. Ikeda; H. M. Shimizu
J. Magn. Magn. Mater., 2007年03月, ［査読有り］

Neutron diffraction experiments with 40T pulsed magnets
K Ohoyama; N Katoh; H Nojiri; Y H Matsuda; H Hiraka; K Ikeda; H M Shimizu
J. Phys.: Conf. Series, 2006年12月, ［査読有り］

Application of miniature pulsed magnets to synchrotron X-ray spectroscopy and neutron diffraction
Y. H. Matsuda; Y. Murata; T. Inami; K. Ohwada; H. Nojiri; K. Ohoyama; N. Katoh; Y. Murakami; F. Iga; T. Takabatake; A. Mitsuda; H. Wada, Synchrotron X-ray and neutron experiments in high magnetic fields have been performed using miniature pulsed magnets. In EuNi2(Si0.18Ge0.82)2, the drastic change of the L3-edge absorption spectrum is found at the valence state transition. While, no changes of the spectra are found at the insulator-metal transitions in Kondo insulators YbB12and Ce3Bi4Pt3. As a test experiment the high field neutron diffraction experiment of MnF2has been carried out at JRR-3M reactor. © 2006 IOP Publishing Ltd.
Journal of Physics: Conference Series, 2006年12月01日

Formation of perovskite-type hydrides and thermal desorption processes in Ca-T-H (T = 3d transition metals)
K. Ikeda; S. Kato; K. Ohoyama; Y. Nakamori; H.T. Takeshita; S. Orimo
Scripta Materialia, 2006年11月, ［査読有り］

Magnetic phase diagrams of Y-diluted antiferromagnet Tb1-xYxB2C2 (0.2 <= x <= 0.5)
Masami Haino; Aya Tobo; Eiichi Matsuoka; Kenji Ohoyama; Hideya Onodera, Magnetic B-T phase diagrams were examined by magnetization and specific heat experiments on the single crystalline Tb1-x,YxB2C2 (0.2 <= x <= 0.5) compounds, and neutron diffraction experiments was performed on the powder (Tb0.5Y0.5B2C2)-B-11 sample. The magnetization curves evidence that the field-induced transition occurs from phase IV into phase II' through a mixed phase of both phases, where phase IV is antiferro magnetic and phase II' is a field-induced phase with the antiferromagnetic and anti ferroquadrupolar order. The mixed phase (IV + II') is enhanced by the Y-dilution, and the lower and upper verges of the mixed phase become clearer in the differential magnetization dM/dB-B curves. The Y-dilution results in scaling down of the ordered phases regions in the B-T space. The ways of scale down of the ordered phase are different between two field directions along the tetragonal [1001 and [110]-axes, that is, the anisotropy of phase stability is increased by the Y dilution. It is supposed that the enhancement of anisotropic phase stability by the Y dilution may be due to the symmetry of the multipoles and the anisotropic multipolar interactions weakened by the Y dilution., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2006年07月, ［査読有り］

Magnetic Properties of the Spin Tetramer Compound Ba6La2Fe4O15
K. Abe; Y. Doi; Y. Hinatsu; K. Ohoyama
Chem. Mater., 2006年

Possible high TQ in YbAl3C3 with 4f 13 system
Masashi Kosaka; Yoshiaki Kato; Chieko Araki; Nobuo Môri; Yoshiki Nakanishi; Masahito Yoshizawa; Kenji Ohoyama; Catalin Martin; Stanley W. Tozer, We report the highest transition temperature of quadrupolar ordering [TQ] in YbAl3C3, where a distinct anomaly is observed by specific heat and ultrasonic measurements at 80 K. Magnetization measurements show only a very slight change and no magnetic or structural phase transitions can be observed by neutron diffraction measurements in this temperature range. Therefore, we believe that YbAl3C3 shows an antiferroquadrupolar ordering with the highest TQ found to date and is the first realization of this ordering beyond liquid nitrogen temperatures for rare-earth and actinide intermetallic compounds. ©2005 The Physical Society of Japan.
Journal of the Physical Society of Japan, 2005年09月, ［査読有り］

Temperature dependence of lattice parameters and anisotropic thermal expansion of bismuth oxide
M Yashima; D Ishimura; K Ohoyama, Temperature dependence of lattice parameters of bismuth sesquioxide (Bi2O3) has been obtained between 26 degrees and 778 degrees C by the Rietveld method using neutron powder diffraction data. Lattice parameters a(alpha)(*), b(alpha)(*), c(alpha)(*), a(delta) and unit-cell volume of alpha and delta phases increased, while the beta angle of alpha phase decreased with an increase of temperature. Here the a(alpha)(*) denotes the lattice parameter a of the alpha phase on the basis of pseudo-fluorite lattice. The thermal expansion coefficients of alpha phase were 26.7, 6.6, and 9.0 ( x 10(-6) degrees C-1) for a(alpha)(*), b(alpha)(*), and c(alpha)(*) axes, respectively, indicating a large anisotropy. The alpha- to -delta phase transition of Bi2O3 was confirmed between 721 degrees and 760 degrees C on heating. At the alpha-delta transition point, the lattice parameters and unit-cell volume discontinuously changed, indicating that the transition is of the first order., BLACKWELL PUBLISHING
JOURNAL OF THE AMERICAN CERAMIC SOCIETY, 2005年08月

Detailed measurements of characteristic profiles of magnetic diffuse scattering in ErB2C2
K Ohoyama; K Indoh; A Tobo; K Kaneko; A Hino; H Onodera, Detailed neutron diffraction measurements were performed on a single crystalline sample of (ErB2C2)-B-II. We observed magnetic diffuse scattering, which consists of three components, just above the transition temperatures. This scattering is also observed in anomalous antiferroquadrupolar ordering compounds, TbB2C2 and HoB2C2. The results of the experiments indicate that the antiferroquadrupolar interaction is not essential for the origin of the magnetic diffuse scattering., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2005年02月, ［査読有り］

Designed performance of high resolution chopper spectrometer at J-PARC
S. Itoh; K. Ohoyama; T. Otomo; K. Nakajima; K. Kuwahara; R. Kajimoto; T. Kamiyama; O. Yamamuro, A designed performance of the high resolution chopper spectrometer of which construction has been proposed at J-PARC to study dynamical properties of materials showing a wide spatial and temporal correlations is summarized.
Journal of Neutron Research, 2005年01月01日, ［査読有り］

Magnetic Properties and Neutron Diffraction Study of Double Perovskites Ca2LnRuO6 (Ln = Y, La-Lu)
C. Sakai; Y. Doi; Y. Hinatsu; K. Ohoyama
J. Phys.: Condens. Matter, 2005年

Structure and Magnetic Properties of the Two-dimensional Antiferromagnet Na2TbO3
Y. Doi; K. Ninomiya; Y. Hinatsu; K. Ohoyama
J. Phys.: Condens. Matter, 2005年

Resonant X-ray scattering on antiferroquadrupolar ordering compound Dy0.8Gd0.2B2C2
Sakata M; Tobo A; Matsumura T; Okuyama D; Murakami Y; Wakabayashi Y; Sawa H; Ohoyama K; Onodera H, Gd substitution in DyB2C2 enhances the antiferromagnetic (AFM) interaction and weakens the antiferroquadrupolar (AFQ) interaction. In Dy0.8Gd0.2B2C2, two successive transitions occur. By performing resonant X-ray scattering measurements, we confirmed the AFQ ordering temperature TQ=18.0K and the N?el temperature TN=19.5K; TN is higher than TQ in Dy 0.8Gd0.2B2C2, in contrast to DyB2C2. There exists an AFM phase between TQ and TN, and the magnetic structure is described by k=[100]. This kind of AFM phase is also observed in HoB2C2 and TbB2C2, although the magnetic structures of these compounds are long-periodic ones. ? 2005 Elsevier B.V. All rights reserved.
PHYSICA B-CONDENSED MATTER, 2005年, ［査読有り］

Revised crystal structure model of Li₂NH by neutron powder diffraction
K. Ohoyama; Y. Nakamori; S. Orimo; K. Yamada
Journal of the Physical Society of Japan, 2005年01月, ［査読有り］

Strctural and magnetic properties of pseudo-two-dimensional triangular antiferromagnets Ba3MSb2O9 (M = Mn, Co, and Ni)
Doi YS; Hinatsu Y; Ohoyama K
JOURNAL OF PHYSICS-CONDENSED MATTER, 2004年12月15日, ［査読有り］

Spin reorientation transition in layered perovskite CaNdFeO4
Oyama S; Wakeshima M; Hinatsu Y; Ohoyama K
JOURNAL OF PHYSICS-CONDENSED MATTER, 2004年11月24日, ［査読有り］

Phase Transitions and Diagrams of Pseudo-Binary Antiferroquadrupolar Ordering Compound Ho_1-xTb_xB_2C_2 (0 ≤ x ≤ 1)
Ido Kaihei; Tobo Aya; Kaneko Koji; Ohoyama Kenji; Onodera Hideya, We performed precise experiments of specific heat and magnetization on single-crystalline samples of pseudo-binary antiferroquadrupolar ordering compounds Ho1-xTbxB2C2 (0 less than or equal to x less than or equal to 1). Although the Tb3+ ions do not participate in the AFQ order in phase III of HoB2C2 that is a coexistent phase of AFQ and antiferromagnetic order, these are cooperative with the AFQ ordering and sustain phase III up to x = 0.6. In Ho0.4Tb0.6B2C2, phase III is separated into phases IIIHo and IIITb, where these are similar to phase III in HoB2C2 and TbB2C2, respectively. This implies that the magnetic structures are different between phases IIIHo and IIITb. It originates in different antiferromagnetic interactions between both compounds., PHYSICAL SOC JAPAN
J. Phys. Soc. Jpn., 2004年07月, ［査読有り］

Impurity-induced ferromagnetism and impurity states in Nd 1/2(Mn0.95M0.05)O3
Y. Moritomo; K. Murakami; H. Ishikawa; M. Hanawa; A. Nakamura; K. Ohoyama, Impurity effects on the lattice structure and the electronic state are investigated for B-site substituted half-doped manganites Nd 1/2Ca1/2(Mn0.95M0.05)O3 (M is the 3d and 4d transition metals). We investigated the interrelation between the impurity-induced ferromagnetism and (1) the lattice structure (chemical pressure effect), (2) the magnitude of the impurity spin, and (3) the density of state (DOS) of the impurity d state at the Fermi level EF. We found a strong correlation between the ferromagnetism and the DOS of the impurity state at EF, suggesting that the ferromagnetism can be ascribed to the enhanced one-electron bandwidth of the Mn 3d-M d hybridized band.
Physical Review B - Condensed Matter and Materials Physics, 2004年06月, ［査読有り］

Impurity-induced ferromagnetism and impurity states in Nd1/2Ca1/2(Mn0.95M0.05)O-3
Y Moritomo; K Murakami; H Ishikawa; M Hanawa; A Nakamura; K Ohoyama, Impurity effects on the lattice structure and the electronic state are investigated for B-site substituted half-doped manganites Nd1/2Ca1/2(Mn0.95M0.05)O-3 ( M is the 3d and 4d transition metals). We investigated the interrelation between the impurity-induced ferromagnetism and (1) the lattice structure (chemical pressure effect), (2) the magnitude of the impurity spin, and (3) the density of state (DOS) of the impurity d state at the Fermi level E-F. We found a strong correlation between the ferromagnetism and the DOS of the impurity state at E-F, suggesting that the ferromagnetism can be ascribed to the enhanced one-electron bandwidth of the Mn 3d-M d hybridized band., AMERICAN PHYSICAL SOC
PHYSICAL REVIEW B, 2004年06月, ［査読有り］

Quadrupolar and magnetic interactions in antiferroquadrupolar ordering compound DyB2C2 studied by Y dilution
K Indoh; A Tobo; K Ohoyama; H Yamauchi; H Onodera, In order to elucidate quadrupolar and magnetic interactions in the antiferroquadrupolar (AFQ) and antiferromagnetic (AFM) ordering compound DyB2C2, neutron diffraction experiments were performed on powdered and single-crystal line samples in addition to reexamination of specific heat and magnetization properties on the Y-diluted system Dy1-xYxB2C2. The results suggest that there is a percolation threshold at x = 0.4-0.5 for the AFQ ordering. The broadening behavior of magnetic reflection peaks by the Y dilution suggests that the AFQ interaction is probably pseudo-one-dimensional with strong AFQ interactions along the c-axis and weak ferroquadrupolar interactions in the c-plane., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2004年06月, ［査読有り］

Unusual antiferromagnetic properties affected by antiferroquadrupolar interaction in TbB2C2
K. Kaneko; N. Metoki; K. Ohoyama; H. Onodera; Y. Yamaguchi, Neutron scattering experiments were carried out on TbB2C2 with T-N = 21.7 K under high energy resolution in order to investigate the diffuse scattering and the incommensurate structure in the antiferromagnetic state. At 3: 9 K, the energy width of both the satellite peak and the diffuse scattering corresponding to the energy resolution of 0: 2 meV. With increasing temperature, only the satellite peak was disappeared far below T-N around 13 K where no anomaly was observed in the specific heat and the magnetic susceptibility. Since the disappearance temperature of the satellites depends on the energy resolution of spectrometer, the dynamical component would affect the incommensurate structure in TbB2C2: (C) 2003 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 2004年05月, ［査読有り］

A new phase boundary in quadrupolar ordered phase of Dy0.9Gd0.1B2C2
H Onodera; J Kaya; H Yamauchi; K Indoh; A Tobo; K Ohoyama; Y Yamaguchi, By specific heat measurements of Dy0.9Gd0.1B2C2, we found a new phase boundary in the antiferroquadrupolar (AFQ) ordered phase with H\\[1 1 0]. It is supposed that the divided AFQ phases differ in arrangements of Dy moments induced by magnetic fields, since there are four possible moment directions in relation to field direction on the complicated AFQ structure. (C) 2003 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 2004年05月, ［査読有り］

Magnetic phase diagrams of antiferroquadrupolar ordering compound DyB2C2
K Indoh; A Tobo; H Yamauchi; K Ohoyama; H Onodera, Specific heat and magnetization measurements were performed precisely on the anfiferroquadruplar (AFQ) ordering compound DyB2C2 in order to reexamine its magnetic B-T phase diagrams. We find new phase boundaries in both diagrams with B parallel to [1 0 0] and B parallel to [1 1 0] and revise the field dependency of some boundaries. In the resultant diagrams, all the phase have closed regions in the B-T space. Two phase boundaries start from T-N in both diagrams with B parallel to [1 0 0] and B parallel to [1 1 0]. The one decreases its transition temperature with increasing held which is the same behavior just to normal anti ferromagnets. The other gradually increases its transition temperature with increasing fields, which seems to satisfy behavior demanded for magnets with spontaneous magnetizations. The new-found boundary divides the previously reported AFQ phase into two phases. The one has magnetically ordered moments oil the AFQ ordered quadrupoles and exists only in magnetic fields. The other is a pure AFQ phase with paramagnetic moments on the ordered quadrupoles., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2004年03月, ［査読有り］

Magnetic properties of y1-xDyxMn6Sn 6 alloys
T. Hori; H. Shiraishi; K. Indoh; K. Ohoyama; A. Tobo; Y. Yamaguchi; T. Sakon; M. Motokawa, We have made magnetization measurements and neutron diffraction experiments on Y1-xDyxMn6Sn6 alloys with hp13 type (MgFe6Ge6 type) structure. The magnetization for the alloys reaches the saturation in a field around 13 T for x = 0, and around 5 T for x ≥ 0.4. The saturated magnetization decreases with increasing x. It is likely that the magnetic moments of Mn atom (μMn = 10μB/Mn atom) and Dy (μDy = 10 μB/Dy atom) are antiferromagnetically coupled to each other. © 2003 Elsevier B.V. All rights reserved., Elsevier
Journal of Magnetism and Magnetic Materials, 2004年

Development of magnetic correlations around the transition temperatures in ErB2C2
K. Ohoyama; A. Hino; K. Indoh; A. Tobo; H. Onodera; Y. Yamaguchi, Elsevier
Journal of Magnetism and Magnetic Materials, 2004年

Quadrupole and hexadecapole ordering in DyB2C2: Direct observation with resonant x-ray diffraction
Y Tanaka; T Inami; SW Lovesey; KS Knight; F Yakhou; D Mannix; J Kokubun; M Kanazawa; K Ishida; S Nanao; T Nakamura; H Yamauchi; H Onodera; K Ohoyama; Y Yamaguchi, Direct evidence of the spatial ordering of Dy 4f quadrupole and hexadecapole moments in DyB2C2 is demonstrated by resonant x-ray diffraction enhanced by an electric quadrupole event (E2 resonance) at the Dy L-III absorption edge. The diffraction data show that the structural phase transition at T-Q=24.7 K is accompanied by a reduction in the symmetry of the Dy site to 2/m, from 4/m, and the spatial ordering of the time-even Dy multipoles with A(g) character. Below T-Q the crystal structure is described by the space group P4(2)/mnm and Dy ions occupy sites (4c). The distortion at T-Q involves the lattice occupied by B and C ions, and it amounts to a buckling of B-C planes that are normal to the two-fold rotation axis of 2/m. An immediately plausible model of low-energy Dy states correlates data on the specific heat, our x-ray diffraction signals, and magnetic ordering below 15.3 K which has been observed in magnetic neutron diffraction., AMERICAN PHYSICAL SOC
PHYSICAL REVIEW B, 2004年01月, ［査読有り］

Crystal and Magnetic Structures of Layered Perovskite CaNdFeO4
OYAMA S; WAKESHIMA M; HINATSU Y; OHOYAMA K
J. Phys., Condens.Matter, 2004年

Spin-reorientation Transition of SrNdFeO4
OYAMA S; WAKESHIMA M; HINATSU Y; OHOYAMA K
J. Physics., Condens.Matter, 2004年

Magnetic properties of tetragonal Ce1-xLuxB2C2 (<= x <= 0.31) compounds
A Tobo; K Ishimoto; J Konno; K Ohoyama; K Kaneko; Y Yamaguchi; H Onodera, Specific heat, dc- and ac-magnetic susceptibility and magnetization measurements were performed on rare earth intermetallic compounds Ce1-xLuxB2C2 (0 less than or equal to x less than or equal to 0.31) in order to elucidate the magnetic interaction in CeB2C2. In the process of the substitution of Cc by Lu in CeB2C2, the characteristics of magnetic transition change from a first-order transition to a second-order one. Furthermore, the spinglass phase appears at Lu concentration x = 0.31. We suppose that the ferromagnetic (FM) and antiferromagnetic (AFM) interactions compete and nearly cancel out each other in CeB2C2, and hence that a biquadratic interaction might cause the first-order magnetic transition at T-N. The Lu substitution breaks the competition between AFM and FM interactions and brings forth randomness in interactions acting on each Ce moment. The typical spin-glass behavior of x = 0.31 originates in this random distribution of magnetic interactions., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2003年12月, ［査読有り］

Magnetic structure of pyrochlore-type Er2Ru2O7
Nobuyuki Taira; Makoto Wakeshima; Yukio Hinatsu; Aya Tobo; Kenji Ohoyama
Journal of Solid State Chemistry, 2003年11月, ［査読有り］

Specific heat and neutron diffraction study on quaternary sulfides BaNd2CoS5 and BaNd2ZnS5
Makoto Wakeshima; Nobuyuki Taira; Yukio Hinatsu; Aya Tobo; Kenji Ohoyama; Yasuo Yamaguchi
Journal of Solid State Chemistry, 2003年08月, ［査読有り］

Anomalous magnetic scattering in tetragonal RB2C2 (R = rare earth) observed by means of neutron diffraction
K. Ohoyama; K. Indoh; A. Tobo; K. Kaneko; H. Onodera; Y. Yamaguchi, Detailed neutron diffraction experiments have been performed on tetragonal R11B2C2 (R = rare-earth) compounds which show characteristic antiferroquadrupolar orderings. TbB2C2, ErB2C2 and HoB2C2, which have magnetic long-periodic states, show anomalous magnetic diffuse scattering with flat intensity. The anomalous diffuse scattering exists in a small region in the reciprocal space, surrounded by satellite peaks, due to the long-periodic magnetic structures. The profile and temperature dependence of the anomalous diffuse scattering indicate that the origin cannot be understood on the basis of magnetic short-range correlations.
Journal of Physics Condensed Matter, 2003年07月23日

Magnetic ordering affected by multipolar interactions in Ho1-xTbxB2C2
K. Ido; A. Tobo; K. Ohoyama; H. Onodera; Y. Yamaguchi, We performed a powder neutron diffraction experiment on Ho1-xTbxB2C2 (x = 0.2, 0.4, 0.6 and 0.8) to compare the magnetic properties of HoB2C2 and TbB2C2. It is found that the magnetic satellite peaks described as k = [1 ± δ1, ±δ1, ±δ2] get larger even in the (antiferromagnetic + antiferroquadrupolar) phase for x = 0.2, 0.4 and 0.6. And a satellite peak around 000 newly emerges for x = 0.4, 0.6 and 0.8.
Journal of Physics Condensed Matter, 2003年07月23日

Spin-glass behaviour of Ce0.69Lu0.31B2C2
K Ishimoto; J Konno; A Tobo; K Kaneko; K Ohoyama; H Onodera; Y Yamaguchi, We have measured the magnetization and ac susceptibility of single-crystalline Ce0.69Lu0.31B2C2. Some features of a spin-glass state were found in the irreversibility between the zero-field-cooled and the field-cooled magnetizations under magnetic fields between 5 and 55 mT in the temperature range from 2 to 10 K and the frequency dependence of the real and imaginary parts of the ac susceptibility (x' and x''). The results indicate the occurrence of a spin-glass transition in Ce0.69Lu0.31B2C2. We suppose the spin-glass behaviour of Ce0.69Lu0.31B2C2 to originate from frustration of magnetic interactions in this compound., IOP PUBLISHING LTD
JOURNAL OF PHYSICS-CONDENSED MATTER, 2003年07月, ［査読有り］

Neutron scattering study on the antiferroquadrupolar order of DyB2C2 under magnetic fields
H Yamauchi; K Ohoyama; S Katano; M Matsuda; K Indoh; H Onodera; Y Yamaguchi, Antiferroquadrupolar (AFQ) ordering in DyB2C2 has been investigated by means of neutron scattering under applied magnetic fields along [110] up to 10 T. In the AFQ ordered phase at 16 K, antiferromagnetic reflections indexed as 00(1)/(2) and 11(1)/(2) are induced by a magnetic field of 1 T. These induced magnetic reflections disappear at 2 T, and develop again, increasing in intensity with increasing field, above 3 T. As temperature increases, the integrated intensity at 4 T shows an anomalous decrease toward similar to13 K in addition to a disappearance at T-Q, while that at 8 T decreases normally toward T-Q. We observed this curious behaviour of the induced magnetic reflections within the AFQ ordered phase., IOP PUBLISHING LTD
JOURNAL OF PHYSICS-CONDENSED MATTER, 2003年07月, ［査読有り］

The concentration-temperature phase diagram of CexLa1-xB2C
A Tobo; H Yamauchi; E Kishi; M Sakata; K Ishimoto; K Ohoyama; H Onodera; Y Yamaguchi, We have synthesized polycrystalline CexLa1-xB2C2 samples and measured the temperature dependence of the low-field magnetization, ac susceptibility and specific heat. As the Ce concentration x decreases, the Neel temperature T-N decreases linearly for x greater than or equal to 0.80. However, the dependence on the concentration x of the transition temperature changes slope at x similar to 0.75. Spin-glass transitions are observed for 0.4 less than or equal to x less than or equal to 0.75. The origin of the spin-glass behaviour will be discussed., IOP PUBLISHING LTD
JOURNAL OF PHYSICS-CONDENSED MATTER, 2003年07月, ［査読有り］

Magnetic phase diagrams of Dy0.8Gd0.2B2C2
H Onodera; K Indoh; J Kaya; M Sakata; H Yamauchi; A Tobo; K Ohoyama; Y Yamaguchi, Gd substitution in DyB2C2, which undergoes an antiferroquadrupolar (AFQ) ordering at T-Q = 24.7 K and an antiferromagnetic (AFM) one at T-N = 15.3 K, enhances the AFM interaction and weakens the AFQ interaction, and the transition sequence at 20% Gd is the reverse of that in DyB2C2. The AFQ transition occurs at T-Q = 17.5 K, below the AFM one at T-N = 19.0 K in Dy0.8Gd0.2B2C2. The present work provides some experimental results on the specific heat and magnetization of Dy0.8Gd0.2B2C2. The magnetic phase diagrams of Dy0.8Gd0.2B2C2 have some resemblance to those of HoB2C2 and Ce0.75La0.25B6. There is an anomalous magnetic phase (named phase IV) that is adjacent to the AFQ phase in each compound., IOP PUBLISHING LTD
JOURNAL OF PHYSICS-CONDENSED MATTER, 2003年07月, ［査読有り］

Addendum to "doping-dependent magnetic structure of Tb 1-xCaxMnO3"
Akihiko Machida; Yutaka Moritomo; Kenji Ohoyama
Journal of the Physical Society of Japan, 2003年05月

High-temperature neutron powder diffraction study of cerium dioxide CeO2 up to 1770 K
M Yashima; D Ishimura; Y Yamaguchi; K Ohoyama; K Kawachi, We have investigated the temperature dependence of unit-cell and structural parameters of ceria (cerium dioxide, CeO2) from room temperature to 1770 K by neutron powder diffraction and the Rietveld method. The unit-cell parameter increases continuously with temperature. It was confirmed that the Debye-Waller factor of oxygen B(O) is larger than that of cerium B(Ce) at any temperature from room temperature to 1770 K. Both B(O) and B(Ce) increase with an increase of temperature. (C) 2003 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV
CHEMICAL PHYSICS LETTERS, 2003年05月, ［査読有り］

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, 2003年05月, ［査読有り］

Magnetic phase diagrams and lattice structure of Nd1/2Ca 1/2(Mn1-yMy)O3 (M = Ru, Cr and Sc)
Sheng Xu; Yutaka Moritomo; Akihiko Machida; Kenji Ohoyama; Arao Nakamura, We have derived the magnetic phase diagram for Nd1/2Ca 1/2(Mn1-yMy)O3 (M = Ru, Cr and Sc) based on the neutron powder diffraction measurements. We found that the Ru- and Cr-doping induces an antiferromagnetic-to-ferromagnetic transition at y = 0.01-0.02, while the Sc-doping does not induce the transition up to y = 0.10. We have found significant dopant dependent effects on the distortion of the MnO6 octahedra in the heavily-doped region of the long-c phase: the MnO6 shape approached to the 2-long/4-short type with Ru-doping, while it does to the 4-long/2-short type with Sc-doping. Absence of the ferromagnetic phase in the Sc-doped system can be ascribed to (1) a strong charge-ordering instability due to the 4-long/2-short type distortion of the MnO6 octahedra and (2) the reduced effective one-electron bandwidth due to the Sc3+ (d0) impurities. ©2003 The Physical Society of Japan.
Journal of the Physical Society of Japan, 2003年04月

Long Periodic Magnetic Structure in CeB2C2　　　　　　　　　　　　　　　
k.ohoyama; k.kaneko; a.tobo; k.ishimoto; h.onodera; y.yamaguchi
Journal of the Physical Society of Japan, 2003年04月01日, ［査読有り］

Ferromagnetic spin-ordering in photo-active RbMn[Fe(CN)(6)]
Y Moritomo; A Kurik; K Ohoyama; H Tokoro; S Ohkosh; K Hashimoto; N Hamada, PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2003年02月, ［査読有り］

Doping-dependent magnetic structure of Tb1-xCa xMnO3
Akihiko Machida; Yutaka Moritomo; Kenji Ohoyama; Arao Nakamura
Journal of the Physical Society of Japan, 2003年01月

High-Temperature Structural Phase Transitions in Strontium Zirconate
OH-UCHI Kenjiro; OKUBE Maki; YASHIMA Masatomo; SAKAI Atsushi; MORI Mizuki; ISHIMURA Daiju; TANAKA Masahiko; OHOYAMA Kenji; MORI Takeharu; YOSHIASA Akira, We have investigated in situ the phase transitions of the strontium zirconate by neutron and high-resolution synchrotron radiation powder diffraction techniques. The unit-cell and structural parameters were refined by the Rietveld method. The sequence of existing phases was confirmed to be Pnma (orthorhombic), Imma (orthorhombic), I4/mcm (tetragonal) and Pm-3m (cubic). The results indicated that the transitions from Pnma to Imma and from I4/mcm to Pm-3m are continuous. The Imma and I4/mcm phases coexisted at 1149K, indicating that the Imma-I4/mcm phase transition is of first order. The tilt angle of ZrO₆ octahedron in Pnma, Imma and I4/mcm decreased with increasing temperature. The tilt angle of ZrO₆ octahedron in the tetragonal phase is taken to be the order parameter and its temperature variation is consistent with a tricritical phase transition., 公益社団法人 日本セラミックス協会
日本セラミックス協会 年会・秋季シンポジウム 講演予稿集, 2003年

Magnetic excitations in the Kondo semiconductor Ybl-'Lu.B12
K. Ohoyama; F. Iga; T. Takabatake; S. Itoh; T. Kamiyama
KENS REPORT-XIV 2001-2002, KEK Pregress Report, 2003年

Crystal Electric Field in TmB2C2
K Ohoyama; H Onodera; K Indoh; T. Kamiyama; S. Itoh; Y. Yamaguchi
KENS REPORT-XIV 2001-2002, KEK Pregress Report, 2003年

Diffuse scattering due to Geometrical Frustration in Mn3O4
Akira KURIKI; Yutaka MORITOMO; Kenji OHOYAMA; Kenichi KATO; Arao NAKAMURA
Journal of the Physical Society of Japan, 2003年, ［査読有り］

Neutron-scattering studies of the field-induced ordered state of TbB2C2
K. Kaneko; S. Katano; M. Matsuda; K. Ohoyama; H. Onodera; Y. Yamaguchi, Neutron-diffraction experiments on single-crystalline Tb11B2C2 were carried out under magnetic fields applied along the [0 1 0] direction. The application of magnetic fields results in the appearance of an antiferromagnetic 1 0 0 reflection above 0.5 T. In consequence, the magnetic structure of a field-induced phase of TbB2C2 can be described with the propagation vectors of the dominant k1 = (1 0 0), k2 = (0 1 1/2) and the additive k3 = (0 0 0), k4 = (0 0 1/2). This result indicates that a field-induced antiferroquadrupolar order is realized in TbB2C2.
Applied Physics A: Materials Science and Processing, 2002年12月

Magnetic structure of tetragonal TmB2C2
K. Ohoyama; K. Kaneko; K. Indoh; A. Tobo; H. Onodera; Y. Yamaguchi, Tetragonal TmB2C2, which is an isostructural compound of antiferroquadrupolar ordering materials DyB2C2 and HoB2C2, is a simple antiferromagnet with well-localised 4 f states. The magnetic structure below TN = 16.5 K is k = [1 0 1/2] type-one with a magnetic moment of 6.5 μB parallel to the c axis, which is different from the fundamental magnetic structure with k = [1 0 0] in the other RB2C2 (R = rare earth) compounds.
Applied Physics A: Materials Science and Processing, 2002年12月

Magnetic and calorimetric studies on 6H-perovskite Ba3TbRu2O9
Doi Y; Wakeshima M; Hinatsu Y; Tobo A; Ohoyama K; Yamaguchi Y
JOURNAL OF ALLOYS AND COMPOUNDS, 2002年10月07日, ［査読有り］

Magnetic correlations in the Cd-Mg-Tb icosahedral quasicrystal
Taku J. Sato; Hiroyuki Takakura; Junqing Guo; An Pang Tsai; Taku J. Sato; Hiroyuki Takakura; Junqing Guo; An Pang Tsai; Kenji Ohoyama, We have carried out powder neutron diffraction experiments on the recently discovered Cd-Mg-Tb quasicrystal. Magnetic long-range order was not detected down to 2.5 K. Instead, short-range correlations develop continuously as temperature is decreased below the spin freezing temperature Tf1 = 12.5 K; no discontinuous change was observed at Tf2 = 5.6 K, where an additional anomaly was found in magnetic susceptibility. The short-range order is mostly identical to that observed in the Zn-Mg-Ho quasicrystal. © 2002 Elsevier Science B.V. All rights reserved.
Journal of Alloys and Compounds, 2002年08月14日, ［査読有り］

Magnetic Order-Order Transition in Tetragonal ErB2C2
Kenji Ohoyama; Kentaro Indoh; Aya Tobo; Hideya Onodera; Yasuo Yamaguchi, We have investigated magnetic properties of ErB2C2 which is an isostructural compound of the antiferroquadrupolar ordering materials, DyB2C2 and HoB2C2, by magnetisation and neutron diffraction measurements. ErB2C 2 shows magnetic transitions at TN = 15.9K and T t = 13.0K. The magnetic structure of the ground state is a simple Ising-type antiferromagnetic one with a propagation vector of k = (1, 0, 0). The intermediate phase between TN and Tt under zero magnetic field is a long range magnetic ordered state with a transverse sinusoidal modulation with a propagation vector of (1 + δ, δ, δ, 0), where δ = 0.1120(2) which is nearly the same as that in phase IV in HoB2C2.
Journal of the Physical Society of Japan, 2002年07月

Magnetic properties of Ce3PbC
M. Kosaka; S. Koiwai; Y. Uwatoko; N. Môri; H. Onodera; K. Ohoyama; H. Abe; H. Kitazawa; G. Kido; T. Kamiyama; H. Noda; T. Omura, Elsevier BV
Physica B: Condensed Matter, 2002年03月, ［査読有り］

Phase separation and ferromagnetic transition in B-site substituted Nd1/2Ca1/2MnO3
A. Machida; Y. Moritomo; K. Ohoyama; T. Katsufuji; A. Nakamura, B-site substitution effects on the structural and magnetic properties are investigated in Nd1/2Ca1/2(Mn0.97M0.03) O3 (M = Al, Zn, Sc, Fe, Ni, Co, and Cr). With decreases of temperature below ∼200 K, these compounds transform into a two-phase state. With further decrease of temperature below ∼100 K, the Cr-, Co-, and Ni-doped compounds show the ferromagnetic transition, while the other compounds show only the antiferromagnetic component. We discuss these dopant-dependent ferromagnetic transition in terms of the effective one-electron bandwidth of the e g band.
Physical Review B - Condensed Matter and Materials Physics, 2002年02月01日

Phase separation and ferromagnetic transition in B-site substituted (formula presented)
A. Machida; Y. Moritomo; K. Ohoyama; T. Katsufuji; A. Nakamura, (formula presented) -site substitution effects on the structural and magnetic properties are investigated in (formula presented) (formula presented) (formula presented) (formula presented) Zn, Sc, Fe, Ni, Co, and Cr). With decreases of temperature below (formula presented) these compounds transform into a two-phase state. With further decrease of temperature below (formula presented) the Cr-, Co-, and Ni-doped compounds show the ferromagnetic transition, while the other compounds show only the antiferromagnetic component. We discuss these dopant-dependent ferromagnetic transition in terms of the effective one-electron bandwidth of the (formula presented) band. © 2002 The American Physical Society.
Physical Review B - Condensed Matter and Materials Physics, 2002年, ［査読有り］

(formula presented) distortion and spin ordering in (formula presented) (formula presented) and 0.65)
Sh. Xu; Y. Moritomo; A. Machida; K. Ohoyama; K. Kato; A. Nakamura, Interrelation between the distortion of the (formula presented) octahedra and spin ordering was investigated for (formula presented) and (formula presented) by means of synchrotron-radiation x-ray powder diffraction and neutron powder diffraction. The ground state of the former (latter) compounds is the (formula presented) orbital-ordered state. A strong orbital-spin coupling is observed in (formula presented) making a sharp contrast with the weak coupling in (formula presented) We interpret the strong coupling in terms of the kinetic energy gain of the (formula presented) carriers in the (formula presented) orbital-ordered state. © 2002 The American Physical Society.
Physical Review B - Condensed Matter and Materials Physics, 2002年, ［査読有り］

Phase transitions in the pseudo-binary compounds Ho1-xTb xB2C2
Kaihei Ido; Hideya Onodera; Kenji Ohoyama; Aya Tobo; Yasuo Yamaguchi, We have performed specific heat experiments on Ho1-xTb xB2C2 (0≤x≤1.0) in order to clarify the similarity and difference between anomalous antiferromagnetic phases of H0B 2C2 and TDB2C2. H0B 2C2 undergoes an antiferromagnetic (AFM) transition at TN= 5.9 K and an an- tiferroquadrupolar (AFQ) transition at T Q= 4.5 K. TDB2C2 shows only an AFM transition at TN= 21.7 K. Although TN changes gradually with increasing x, TQ hardly decreases up to x = 0.6. This unusual result indicates that the Tb atoms seem to support the AFQ order in H0B 2C2. However, judging from an entropy change at T Q, it is supposed that the Tb atoms do not participate in the AFQ order. © 2002 The Physical Society of Japan., Physical Society of Japan
Journal of the Physical Society of Japan, 2002年

Neutron Scattering Study on the Orbital Order of DyB2C2 in Magnetic Fields
Hiroki Yamauchi; Kenji Ohoyama; Masugu Sato; Susumu Katano; Hideya Onodera; Yasuo Yamaguchi, Antiferroquadrupolar (AFQ) ordering in DyB2C2 has been investigated by neutron scattering under applied magnetic.fields. In the AFQ ordered phase, antiferromagnetic reflections indexed as 1 0 1/2, 1 0 1 and 1 0 3/2 appear upon applying magnetic fields, and develop with fields up to 2.5T. These field induced AFM reflections are clear evidence of the AFQ order in DyB2C2. Experimental result shows that the induced magnetic dipolar moments are strongly suppressed by the AFQ order of the Dy quadrupolar moments. A possible model of this magnetic ordering is proposed., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2002年01月, ［査読有り］

Proposal for a chopper spectrometer with very high energy resolution
K. Ohoyama; S. Itoh; T. Otomo; T. Osakabe; J. Suzuki; M. Matsuda; K. Kuwahara; M. Arai
Appl. Phys. A, 2002年, ［査読有り］

Neutron Investigation of Tb1-xCaxMnO3 (x ≥ 0.5)
Akihiko Machida; Yutaka Moritomo; Kenji Ohoyama; Arao Nakamura, Crystal and magnetic structures of Tb1-xCaxMnO3 (x ≥ 0.5) have been investigated by means of neutron powder diffraction experiments. We have derived the magnetic phase diagram against hole concentration x and temperature T: the spin structure changes as CE- → C- → G-type structure with increase of x. In the vicinity of the magnetic phase boundaries, magnetically phase separated state has been observed. At high temperature region, we observe the metallic behavior in a wide x region (0.70 ≤ x ≤ 0.95), and ascribe it to the enhanced one-electron bandwidth W of the eg state.
Journal of the Physical Society of Japan, 2001年12月

Systematic study on crystal structures in tetragonal RB2C2 (R=rare earth) compounds
K Ohoyama; K Kaneko; K Indoh; H Yamauchi; A Tobo; H Onodera; Y Yamaguchi, Detailed crystal structures of the tetragonal RB2C2 (R=La, Ce, Pr, Nd, Tb, Dy, Ho, Er, Tm and Lu) compounds which include the antiferroquadrupolar ordering materials, DyB2C2 and HoB2C2, have been investigated by neutron powder diffraction technique. RB2C2 are crystallised in the same LaB2C2 type crystal structure with P4/mbm symmetry. The structure of the B-C network which consists of non-regular squares and octagons are nearly the same in the system except slight rotation as rare earth atoms become heavier., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2001年11月, ［査読有り］

Antiferroquadrupolar ordering in the pseudo-binary tetragonal compounds Ho1-xDyxB2C2
H Shimada; H Onodera; H Yamauchi; A Tobo; K Ohoyama; Y Yamaguchi, Antiferroquadrupolar (AFQ) and antiferromagnetic (AFM) transitions in Ho1-xDyxB2C2 (0 less than or equal to s less than or equal to 1.0) have been investigated on the single-crystalline samples by magnetization and specific heat measurements. As the Dy concentration increases, the both transition temperatures increases from T-Q = 3.5 K and T-N = 5.9K for x = 0 to T-Q = 24.7K and T-N = 15.3K for x = 1. For x = 0.2 and 0.3, there appears a single transition at which the AFQ and AFM transitions occur simultaneously. For 0.4 less than or equal to x, the two transition temperatures are reversed. The temperature dependence of specific heat is interpreted well by assuming that the entropy of R ln 3 is released through the successive transitions in HoB2C2, that is, the 4f ground state of Ho3+ ion is a quasi-triplet. It is supposed that the Ho3+ ion has a rather small quadrupolar moment compared with the Dy3+ quadrupole., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2001年06月, ［査読有り］

Novel magnetic behavior in RB2C2: competitive coexistence of antiferroquadrupolar and antiferromagnetic order
H Yamauchi; H Onodera; K Kaneko; A Tobo; K Ohoyama; Y Yamaguchi, Magnetic properties of tetragonal compounds DyB2C2 and HoB2C2 are investigated by magnetization, specific heat and neutron diffraction experiments. An antiferroquadrupolar (AFQ) ordering occurs below T-Q = 24.7 K with a successive magnetic transition at T-N = 15.3 K in DyB2C2. In contrast to DyB2C2, an AFQ transition in HoB2C2 occurs at 4.5K below an antiferromagnetic transition temperature at 5.9 K. (C) 2001 Elsevier Science BY. All rights reserved., ELSEVIER SCIENCE BV
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 2001年05月, ［査読有り］

Crystal Structures and Magnetic Properties of the 6H-Perovskite Ba₃LnRu₂O₉ (共著)
DOI Y; WAKESHIMA M; HINATSU Y; TOBO A; OHOYAMA K; YAMAGUCHI Y
J. Mater. Chem., 2001年

Magnetic correlations in the Zn-Mg-rare-earth icosahedral quasicrystals
Taku J. Sato; Hiroyuki Takakura; An Pang Tsai; Kenji Ohoyama; Kaoru Shibata; Ken H. Andersen, The previously reported magnetic long-range order has been revisited in the Zn-Mg-rare-earth systems by means of neutron diffraction, magnetic susceptibility and microstructural analysis. It was found that the long-range order is absent in icosahedral quasicrystals, where only short-range spin correlations develop even at the lowest temperatures. The long-range order was attributed to the (ZnxMg1-x)5-rare-earth crystalline phase, which was shown to be a contaminating phase in the previously used samples. The short-range spin correlations have been investigated in detail by single quasicrystal neutron scattering. A close relation has been suggested between the short-range correlations and the quasiperiodic structure.
Materials Science and Engineering A, 2000年12月15日, ［査読有り］

Electron doping effects in conducting Sr2FeMoO6
Y. Moritomo; Sh Xu; T. Akimoto; A. Machida; N. Hamada; K. Ohoyama; E. Nishibori; M. Takata; M. Sakata, Effects of the electron doping on the magnetic and electronic properties have been investigated in the conducting double perovskite Sr2FeMoO6. Judging from the enhanced moment μMo at the Mo site, the doped electrons are considered to occupy mainly the down-spin Mo4d band. Filling dependence of the saturation magnetization Ms, the spin-wave stiffness coefficient Ds and thy γ coefficient are discussed on the basis of a LDA + U band calculation. We further discuss possible origins for the magnetism.
Physical Review B - Condensed Matter and Materials Physics, 2000年12月01日

Pressure effect and neutron scattering study on A(x) HfNCl (A; alkali metals and organic molecules)
S Shamoto; K Iizawa; T Koiwasaki; M Yasukawa; S Yamanaka; O Petrenko; SM Bennington; H Yoshida; K Ohoyama; Y Yamaguchi; Y Ono; Y Miyazaki; T Kajitani, The transition temperature of NaxHfNCl (T-c(max) =20.0 K) is found to be lower than that of Li0.5THFyHfNCl (T-C=24.0 K), Pressure effect on Na0.3HfNCl (T-C=19.4 K) is found to be small, i.e., dT(C)/dP =-0.013(6) K/kbar. Powder neutron inelastic scattering on Na0.3HfNCl shows the increase in S(Q,E) at anomalous high energy, i.e,, about 30 meV, in comparison with 2 Delta similar to8 meV with decreasing temperature from 25 to 10 K., ELSEVIER SCIENCE BV
PHYSICA C, 2000年11月, ［査読有り］

Microdomain structure of Cr-doped manganites: Nd1/2Ca1/2(Mn,Cr)O3
Akihiko Machida; Yutaka Moritomo; Eiji Nishibori; Masaki Takata; Makoto Sakata; Kenji Ohoyama; Shigeo Mori; Naoki Yamamoto; Arao Nakamura, Crystal and magnetic structures of Cr-doped manganites. Nd1/2Ca1/2Mnl-yCryO3 (y = 0.00 and 0.03), have been investigated by synchrotron radiation (SR) x-ray powder diffraction as well as neutron powder diffraction measurements. A detailed analysis of the high-resolution x-ray profile has revealed that the Cr-doped compound exhibits broad extra reflections, suggesting the formation of microdomains below the charge-ordering temperature TCO. The origin of the microdomain structure is discussed in terms of the charge separation.
Journal of the Physical Society of Japan, 2000年11月

Characteristic magnetic structure due to antiferroquadrupolar ordering in (HoB2C2)-B-11
K Ohoyama; H Yamauchi; A Tobo; H Onodera; H Kadowaki; Y Yamaguchi, We determined the magnetic structures of the antiferroquadrupolar (AFQ) ordering material with a tetragonal crystal structure, (HoB2C2)-B-11, by neutron diffraction technique. The ground state of (HoB2C2)-B-11 below T-Q shows a characteristic magnetic structure due to competitive coexistence of AFQ and antiferromagnetic (AFM) interactions, which is basically the same as that of the other tetragonal AFQ material DyB2C2. An angle of 70 degrees between adjacent magnetic moments along [0 0 1] indicates that the main component of magnetic couplings along [0 0 1] in the ground state is ferromagnetic one, which is strongly affected by AFQ interactions. The existence of the intermediate magnetic ordered phase, phase IV, above T-Q indicates that the AFQ ordering in (HoB2C2)-B-11 at T-Q is a rare case which is realised in a magnetic ordered state. The magnetic structure in phase IV is a long period one caused by a short range magnetic ordering with a characteristic energy of about 9K which is higher than T-N. The suppressed magnetic entropy at T-N is, therefore, attributed to the short range magnetic ordering., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2000年10月, ［査読有り］

Antiferromagnetic structure with the uniaxial anisotropy in the tetragonal LaB2C2 type compound, NdB2C2
K Ohoyama; T Onimaru; H Onodera; H Yamauchi; Y Yamaguchi, We report magnetic properties and the phase diagram of NdB2C2 which has the same tetragonal LaB2C2 crystal structure as that of the antiferroquadrupolar ordering material, DyB2C2. NdB2C2 is an uniaxial anisotropic antiferromagnet with T-N = 8.8 K. The propagation vector in the magnetic ordered state below T-N is k = [100]; the coupling between the nearest neighbour magnetic moments in the c-plane is antiferromagnetic, and that along the [001] direction is ferromagnetic., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2000年08月, ［査読有り］

Possible field-induced antiferroquadrupolar ordered phase in HoB2C2
H Yamauchi; H Onodera; K Ohoyama; Y Yamaguchi, Magnetic properties were investigated on the single-crystalline HoB2C2 compound with the tetragonal structure. An antiferromagnetic (AFM) transition occurs at T-N = 5.8 K. At T-Q = 5.0 K, a spin-reorientation transition occurs, and spontaneous magnetization appears along the [1 0 0]- and [1 1 0]-axis. The magnetization behavior below T-Q is well interpreted by postulating the magnetic structure similar to that of the antiferroquadrupolar (AFQ) ordering compound DyB2C2. Below T-Q the AFQ ordering coexists competitively with the AFM ordering. The pure AFQ ordered phase is confirmed only in the magnetic fields applied along the [1 1 0]-axis. (C) 2000 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV
PHYSICA B, 2000年06月, ［査読有り］

Effect of pressure on the ferroquadrupolar compound TmAu2
M Kosaka; Y Uwatoko; T Seino; H Onodera; K Ohoyama; Y Yamaguchi; M Ohashi, TmAu2 with a simple body-centered tetragonal MoSi2-type structure undergoes an electric transition to a ferroquadrupolar ordered state at T-Q of 7.0 K and a magnetic transition to an antiferomagnetic state at T-N Of 3.2 K, We have measured pressure dependence of electrical resistivity on single-crystalline TmAu2 sample. The results reveal that the T-N decreased with increasing pressure (partial derivative T-N/partial derivative P = - 4.54 mK/kbar), while the T-Q increased with increasing pressure (partial derivative T-Q/partial derivative P = 21.5 mK/kbar). (C) 2000 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE BV
PHYSICA B, 2000年06月, ［査読有り］

Effects of Y dilution on the antiferroquadrupolar ordering in the tetragonal compound DyB2C2
S Sako; H Onodera; H Yamauchi; K Indoh; A Tobo; K Ohoyama; Y Yamaguchi, Antiferroquadrupolar (AFQ) and magnetic transitions in Dy1-xYxB2C2 (0 less than or equal to x less than or equal to 0.6) have been investigated on the single-crystalline samples by magnetization and specific heat measurements. As the Y concentration increases, the magnetic transition temperature decreases from 15.3 K at x = 0 to 4.5 K at a = 0.6. The AFQ transition temperature also decreases from 24.7 K at x = 0 to 7.4K at x= 0.6. although it becomes unclear fur x greater than or equal to 0.5 in the magnetization. A lambda-type peak of specific heat at To becomes broader as x increases, and changes to a small upheaval for x greater than or equal to 0.5. On the other hand, the field-induced transitions at the boundary between the AFQ and paramagnetic phases are clearly observed in the magnetization processes at 1.5 K x less than or equal to 0.6. The behavior of specific heat implies that the AFQ interaction acts strongly in a rather shorter distance than the antiferromagnetic interaction in DyB2C2. The Y dilution causes in a wide distribution of the AFQ interaction strength acting on the Dy quadrupoles. Then the AFQ order developes in a wide temperature range, and is almost completed above the magnetic transition temperature., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2000年06月, ［査読有り］

Neutron powder diffraction study on B-C network atomic arrangements in tetragonal CeB2C2
Koji Kaneko; Kenji Ohoyama; Hideya Onodera; Yasuo Yamaguchi, Physical Society of Japan
Journal of the Physical Society of Japan, 2000年

Antiferromagnetic spin correlations in the Zn-Mg-Ho icosahedral quasicrystal
Taku J. Sato; Hiroyuki Takakura; An Pang Tsai; Kaoru Shibata; Kenji Ohoyama, Magnetic diffuse scattering in the Zn-Mg-Ho icosahedral quasicrystal has been studied by neutron scattering over a wide (Formula presented) range using a single-quasicrystalline sample. It was found that the diffuse scattering obeys the icosahedral symmetry, and appears as satellite peaks of the intense nuclear Bragg reflections. The diffuse-scattering patterns were successfully accounted for by assuming short-range spin correlations in a six-dimensional hypercubic crystal with a magnetic modulation vector (Formula presented) A possible origin for the six-dimensional spin correlations is discussed. © 2000 The American Physical Society.
Physical Review B - Condensed Matter and Materials Physics, 2000年, ［査読有り］

Magnetic and Neutron Diffraction Study on Iridium((]G0004[))Perovskites Sr=LnIrO₆(Ln=Ce,Tb)(共著)
HARADA D; WAKESHIMA M; HINATSU Y; OHOYAMA K; YAMAGUCHI Y
Journal fo Physics: Condensed Matter, 2000年

Magnetic properties of the tetragonal compounds CeB2C2 and PrB2C2
H. Onodera; K. Kaneko; T. Onimaru; K. Ohoyama; Y. Yamaguchi; H. Kobayashi; Y. Nemoto; T. Goto
J. Magn. Magn. Mater., 2000年, ［査読有り］

Spin dynamics in S = 3/2 one-dimensional Heisenberg antiferromagnets CsVCl3 and CsVBr3
Shinichi Itoh; Yasuo Endoh; Kazuhisa Kakurai; Hidekazu Tanaka; Steve M. Bennington; Toby G. Perring; Kenji Ohoyama; Mark J. Harris; Kenji Nakajima; Chris D. Frost, The spin dynamics in S=3/2, one-dimensional (ID) Heisenberg antiferromagnets, CsVCl3 and CsVBr3, was investigated using inelastic neutron scattering. The magnetic excitations were measured at temperatures above the three-dimensional ordering temperature in order to discuss the ID properties in the present systems. We report on the spin dynamics at low temperatures and its temperature (7) dependence. From the observed dispersion relation, using the renormalization constant calculated from the quantum Monte Carlo method, we obtained the exchange constant (J) in good agreement with those taken from bulk-susceptibility measurements. The observed structure factor was well described by that calculated from the parameters describing the dispersion relation. The energy width (・｡) was independent of the ID momentum transfer (q) at large energy transfers, however, its q dependence exhibits the minimum at the magnetic zone center. The parameters describing the energy scale in the spin dynamics at low T were found to be scaled by J. We also investigated the T dependence of the spin dynamics: ・｡(T) can be scaled by J, ・｡(T) at T>J is proportional to T as predicted by classical theory but at T>J, F decreases with decreasing T and becomes finite. On the other hand, we found that ・ﾈ(T) is proportional to T at any T. The scaling by J in the dynamics at low T as well as ・｡(T) suggests that the observed spin dynamics is of ID origin. We conclude that the spin dynamics at high temperatures T>J, is well described by classical theory, ho
Physical Review B - Condensed Matter and Materials Physics, 1999年12月01日, ［査読有り］

Evidence of antiferroquadrupolar ordering of DyB2C2
Y Tanaka; T Inami; T Nakamura; H Yamauchi; H Onodera; K Ohoyama; Y Yamaguchi, The antiferroquadrupolar ordering in DyB2C2 has been investigated using the x-ray resonant scattering technique. The dependence of the intensities of two superlattice peaks on temperature, azimuthal angle, and energy of the incident x-rays was measured. The results show that the antiferroquadrupole ordering, which accompanies a structural phase transition, exists below T-Q = 25 K. A structural model for the antiferroquadrupole ordering, for which the propagation vectors are (0, 0, 1/2) and (0, 1, 1/2), is presented., IOP PUBLISHING LTD
JOURNAL OF PHYSICS-CONDENSED MATTER, 1999年11月, ［査読有り］

Magnetic structure modified by the quadrupolar interaction in DyB2C2
H Yamauchi; H Onodera; M Ohashi; K Ohoyama; T Onimaru; M Kosaka; Y Yamaguchi, Elsevier BV
Journal of Physics and Chemistry of Solids, 1999年09月, ［査読有り］

Hydrogen in beta-ZrNCl
S Shamoto; K Iizawa; T Kato; M Yamada; S Yamanaka; K Ohoyama; M Ohashi; Y Yamaguchi; T Kajitani, Position and content of hydrogen atoms in as-transported HxZrNCl, which is the parent compound of a novel two-dimensional superconductor Li0.16ZrNCl with T-c = 15 K, are determined by powder neutron diffraction. Hydrogen atoms are found to occupy 6c site with z = 0.235, which is located between ZrN and Cl layers, and with an occupancy, g = 0.4, i.e. x = 0.4. (C) 1999 Elsevier Science Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS, 1999年08月, ［査読有り］

Short-range spin order and magnetic excitations in diluted magnetic semiconductor Zn0.568Mn0.432Te
Y Ono; S Shamoto; K Sato; T Kamiya; T Sato; Y Oka; Y Yamaguchi; K Ohoyama; Y Morii; T Kajitani, The diluted magnetic semiconductor, Zn0.568Mn0.432Te, is studied by means of neutron diffraction and cold neutron scattering below 100 K. Distribution of magnetic diffuse scattering intensity indicates the coexistence of two kinds of antiferromagnetic short-range orders, i.e. type-III and type-I in a face centered cubic Mn sublattice. The type-I short-range order component decreases below spinglass transition temperature, T-g = 17 K, by applying a magnetic field of 5 Tesla. We newly found a marked increase of quasi-elastic scattering intensity at T-g and an unknown broad inelastic peak lying around 1.0 meV at 14 K. (C) 1999 Elsevier Science Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS, 1999年08月, ［査読有り］

Multi-magnetic-mode in (Cr1-xMnx)(2)As
Y Yamaguchi; K Ohoyama; T Kanouchi; M Ohashi; K Ishimoto, Concentration and temperature dependence of the magnetic structure is investigated by means of powder neutron diffraction on the compounds of (Cr1-xMnx)(2)As system for the concentration range of 0 less than or equal to x less than or equal to 0.5. There are two cation sites, A and B, in this crystal structure, and Mn atoms preferred to occupy site-B. The magnetic structure realized in this system is found to be such a special one that isotropic exchange interactions cancel out between site-A and B cations for the whole range of the present investigation. The site-A and B cations behave independently with each other, as the former aligns at T-t and the latter at T-N. (C) 1999 Elsevier Science Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS, 1999年08月, ［査読有り］

Crystal structure of tetragonal (CeB2C2)-B-11
T Onimaru; H Onodera; K Ohoyama; H Yamauchi; M Ohashi; Y Yamaguchi, Neutron powder diffraction experiments were performed in order to determine the crystal structure of (CeB)-B-11 C-2(2), since the structure of CeB2C2 has been examined only by X-ray techniques and the positions of the B and C atoms in this compound are suspicious. The neutron diffraction pattern reveals that the crystal structure of (CeB)-B-11 C-2(2) has a symmetry with the space group of P4/mbm, where the Ce atoms occupy the 2(a) sites (0,0,0) and the B and C atoms 4(h) sites (x,x + 0.5,0.5) with positional parameters of X-B = 0.361(1) and x(C) = 0.160(1) at 15.0 K. (C) 1999 Elsevier Science Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS, 1999年08月, ［査読有り］

Neutron powder diffraction on (CeB2C2)-B-11 and (NdB2C2)-B-11: A new model for the tetragonal crystal structure
T Onimaru; H Onodera; K Ohoyama; H Yamauchi; Y Yamaguchi, Crystal structures of CeB2C2 and NdB2C2 were investigated by means of neutron powder diffraction using B-11 enriched samples. Diffraction patterns of (CeB2C2)-B-11 and (NdB2C2)-B-11 are very similar to each other, and Rietveld analyses reveal that the crystal structure belongs to a symmetry group of tetragonal P4/mbm. where the rare earth atoms occupy 2(a) sites and the B and C atoms occupy two 4(h) sites with different positional parameters. The newly determined structure differs from previously reported ones with P4/mbm and P (4) over bar 2c mainly in the site positions occupied by the B and C atoms. The B and C atoms form network planes consisting of non-regular squares and octagons., PHYSICAL SOCIETY JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 1999年07月, ［査読有り］

Antiferroquadrupolar ordering and magnetic properties of the tetragonal DyB2C2 compound
H Yamauchi; H Onodera; K Ohoyama; T Onimaru; M Kosaka; M Ohashi; Y Yamaguchi, Magnetic properties were investigated on a single-crystalline DyB2C2 compound with the tetragonal structure. Spontaneous magnetizations appear along the a- and [110]-directions below T-c = 15.3 K. A very small sholder is observed only along the c-axis at T-Q = 24.7 K, although large lambda-type anomalous specific heats are observed at T-C and T-Q. There exists a large magnetic anisotropy in the tetragonal basal plane which is observed in magnetization processes below T-C. Neutron powder diffraction experiments reveal that magnetic reflections are observed only below T-C. In the magnetically ordered phase, the Dy moments are arranged to he perpendicular to neighbours along the c-axis. The results are well interpreted by postulating that the phae between T-C and T-Q is an antiferroquadrupolar ordered one. DyB2C2 is a novel compound with a high antiferrocluadrupolar ordering temperature of 24.7 K., PHYSICAL SOCIETY JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 1999年06月, ［査読有り］

Hole-concentration-induced transformation of the magnetic and orbital structures in Nd1-xSrxMnO3
R. Kajimoto; H. Yoshizawa; H. Kawano; H. Kuwahara; Y. Tokura; K. Ohoyama; M. Ohashi, We have peformed neutron diffraction measurements on melt-grown polycrystalline samples of Nd1-xSrxMnO3(0.49 <
x <
0.75). A systematic transformation of the crystalline and magnetic structures of this system was observed. This can be consistently explained by the change of the character of the Mn egorbitals. When increasing X, the Nd1-xSrxMnO3system exhibits an evolution from a metallic ferromagnetic state, to a metallic A-type antiferromagnetic (AFM), and then to an insulating C-type AFM state. The CE-type charge-ordered AFM state was observed only in the vicinity of x = 1/2 and it coexists with the A-type AFM state for x ≳ 1/2, indicating that the energy difference between these two states is very small. We also found that the MnO6octahedra are apically compressed in the CE-type and A-type AFM states due to the d(3x2-r2)/d(3y2-r2) or d(x2-y2) orbital ordering, whereas they are apically elongated by the rod-type d(3z2-r2) orbital ordering in the C-type AFM state. Finally, a selective broadening of Bragg peaks was observed in the C-type AFM phase and its x dependence strongly suggests the onset of charge ordering for either x=4/5 or x=3/4. © 1999 The American Physical Society.
Physical Review B - Condensed Matter and Materials Physics, 1999年, ［査読有り］

Magnetic excitations in the Kondo compound CeRhSb
K. Ohoyama; M. Kohgi; T. Yoshino; T. Takabatake; W. Hahn; R. S. Eccleston, High energy magnetic excitations in the Kondo compound with the ε-TiNiSi type crystal structure, CeRhSb, were observed by inelastic neutron scattering. The magnetic excitation spectrum at 17 K shows a broad inelastic peak which is well reproduced by the Lorentzian spectral function centred at E0 = 32 ± 4 meV with a half width of ∼ E0. © 1999 Elsevier Science B.V. All rights reserved., Elsevier
Physica B: Condensed Matter, 1999年

Magnetism of CaNiN
S. Shamoto; T. Kato; K. Ohoyama; M. Ohashi; Y. Yamaguchi; T. Kajitani, Powder neutron diffraction measurement of CaNiN exhibits no structural phase transition and no long range magnetic ordering with above 0.2μB from room temperature to about 3 K. Temperature independent paramagnetic susceptibility and specific heat measurement show that the maximum Wilson ratio is about 1.5, indicating a relatively weak electron correlation effect in CaNiN., Elsevier Science Ltd
Journal of Physics and Chemistry of Solids, 1999年

Crystal field splitting in the heavy fermion compounds Ce2X (X = Sb,Bi)
K. Ohoyama; H. Hayashi; H. Onodera; M. Ohashi; Y. Yamaguchi; M. Kohgi; T. Suzuki; K. Hirota; S. Ikeda, We performed inelastic neutron scattering experiments on polycrystalline samples of the heavy fermion compounds Ce2X (X = Sb, Bi). We observed a well-defined magnetic peak at 5.4 ± 0.1 meV in an inelastic spectrum of Ce2Bi at 21 K, which indicates that Ce2Bi includes well localised 4f states. In contrast, Ce2Sb shows only broad magnetic scattering with a small magnetic peak at about 1.5 meV at 21 K., Elsevier Science Ltd
Journal of Physics and Chemistry of Solids, 1999年

Structural study on novel two-dimensional superconductor NaxHfNCl
S. Shamoto; K. Iizawa; M. Yamada; K. Ohoyama; Y. Yamaguchi; T. Kajitani, The structure of the novel two-dimensional superconductor, NaxHfNCl (x = 0.29, Tc = 20 K) is determined by powder neutron diffraction measurement. NaxHfNCl is isomorphous to Li0.16ZrNCl, which also exhibits superconductivity with Tc = 15 K. The nearest interatomic distance of Hf-Hf (3.24 angstrom at 4 K) is longer than that of Zr-Zr (3.10 angstrom at 4 K) in Li0.16ZrNCl. This structural change corresponds to the decrease in the transfer integral of the d bands in the Hf system, i.e. tHf/tZr approx. 0.85, indicating the enhancement of the density of states in NaxHfNCl., Elsevier Science Ltd
Journal of Physics and Chemistry of Solids, 1999年

Neutron scattering study of antiferromagnetic correlations in the Zn-Mg-Ho icosahedral quasicrystal
Taku J. Sato; Hiroyuki Takakura; An Pang Tsai; Kaoru Shibata; Kenji Ohoyama; Ken H. Andersen, Magnetism in the Zn-Mg-Ho icosahedral quasicrystal has been studied by neutron scattering. Powder samples of the icosahedral and related crystalline phases were reexamined to clarify the origin of the previously-reported long-range magnetic order [Charrier et al., Phys. Rev. Lett. 78 (1997) 4637]. The long range order was found to originate from the related crystalline phase, which is a contaminant in the previously-used samples. Whereas for high-quality icosahedral phase, we could detect only magnetic diffuse scattering. This apparently shows the absence of the long range order in the icosahedral phase. The diffuse scattering was studied in detail by using a single quasicrystalline sample. It was found that the diffuse scattering appears as satellites from intense nuclear Bragg reflections. This indicates that corresponding spin correlations can be regarded as developed between spins on the six-dimensional virtual hypercubic lattice. A magnetic modulation vector for the correlations is proposed.
Materials Research Society Symposium - Proceedings, 1999年, ［査読有り］

Magnetic ordering of the edge-sharing CuO2 chains in Ca2Y2Cu5O10
M Matsuda; K Ohoyama; M Ohashi, A neutron powder diffraction study revealed that Ca2Y2Cu5O10, which consists of edge-sharing CuO2 chains, shows an antiferromagnetic long-range ordering below similar to 29 K. The arrangement of the Cu2+ spins is ferromagnetic along the chain (a axis) with a spin direction along the b axis. The magnetic structure has the propagation vector k = [001]. The ordered moment of the Cu2+ spins is similar to 0.9 mu(B) at 10 K; suggesting that the interchain interactions are fairly large. The observed intensities can he better described by assuming an ordering of oxygen moments which are induced due to the strong hybridization between the copper and oxygen ions., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 1999年01月, ［査読有り］

Neutron scattering study of the Zn-Mg-Ho icosahedral quasicrystal
T. J. Sato; H. Takakura; A. P. Tsai; K. Shibata; K. Ohoyama; K. H. Andersen, Magnetic diffuse scattering from the Zn-Mg-Ho icosahedral quasicrystal has been observed by single-crystal neutron-scattering for a wide qq-region. The diffuse scattering appears as satellites of intense nuclear Bragg reflections. This suggests that corresponding short-range spin correlations have a modulation vector defined in the six-dimensional reciprocal-lattice space. The modulation vector is proposed as qqm = (3/4, 0, 0, 1/2 , 3/4, 1/2 ).
Journal of Physics and Chemistry of Solids, 1999年, ［査読有り］

Magnetic structure of C14 Laves phase DyMn2
K Inoue; Y Nakamura; Y Yamaguchi; K Ohoyama; M Ohashi; AV Tsvyashchenko; L Fomicheva, PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 1998年12月, ［査読有り］

Structures of β-ZrNCl and Superconducting Li_0.16ZrNCl: Double Honeycomb Lattice Superconductor
S. Shamoto; T. Kato; Y. Ono; Y. Miyazaki; K. Ohyama; M. Ohashi; Y. Yamaguchi; T. Kajitani
PHYSICA C, 1998年, ［査読有り］

Neutron-scattering study of DyB6
K. Takahashi; H. Nojiri; K. Ohoyama; M. Ohashi; Y. Yamaguchi; M. Motokawa; S. Kunii, We report the first neutron-diffraction experiment on heavy rare-earth hexaboride DyB6. The results indicate that the structural phase transition occurs at 30 K and the antiferromagnetic order at TN = 26 K. Magnetic structure below TN is found to be triple-κ spin structure with the propagation vector κ = 〈1/4 - 1/4 1/2〉. © 1998 Elsevier Science B.V. All rights reserved., Elsevier
Journal of Magnetism and Magnetic Materials, 1998年

Quadrupole ordering and magnetic properties of tetragonal TmAg2
M. Kosaka; H. Onodera; K. Ohoyama; M. Ohashi; Y. Yamaguchi; S. Nakamura; T. Goto; H. Kobayashi; S. Ikeda
PHYSICAL REVIEW B, 1998年, ［査読有り］

Lattice effects on the charge-ordering transition in R0.5Sr1.5MnO4
Y Moritomo; A Nakamura; S Mori; N Yamamoto; K Ohoyama; M Ohashi, Magnetic and transport properties are investigated for single crystals of layered-type-doped manganites R0.5Sr1.5MnO4 with systematic variation of the averaged radius r(R) of the trivalent rare-earth ions R3+ La0.5Sr1.5MnO4 (R = La) shows a charge-ordering (CO) transition at T-CO = 230 K. With a decrease of the in-plane Mn-O bend length d(Mn-O(in)), T-CO decreases and eventually the transition disappears for R = Nd. Such a remarkable lattice effect on the CO transition is in sharp contrast to the negligible lattice effect in the isostructural layered nickelates., AMERICAN PHYSICAL SOC
PHYSICAL REVIEW B, 1997年12月, ［査読有り］

Ferromagnetic-antiferromagnetic transition of itinerant electron magnets Mn3-xFexSi
H. Miki; K. Ohoyama; H. Onodera; H. Yamauchi; Y. Yamaguchi; H. Nojiri; M. Motokawa; S. Funahashi; S. Tomiyoshi, By combining both neutron diffraction and magnetization measurements the magnetic phase diagram is completed for Mn3-xFexSi system. The antiferromagnetism is realized in x < 1.25, and then ferromagnetism appears in x ≥ 1.25. The Néel temperature increases gradually with increasing x, and the Curie temperature for x > 1.25 seems to continue smoothly from the value of TN. In the low temperature region for x ≥ 1.25, canting ferromagnetism takes place., Elsevier
Physica B: Condensed Matter, 1997年07月, ［査読有り］

Magnetic excitations in the antiferromagnet Fe-doped Mn3Si
H. Miki; K. Ohoyama; Y. Yamaguchi; K. Nakajima; S. Tomiyoshi, The inelastic neutron scattering due to the magnetic excitation in a single crystal of itinerant electron antiferromagnet Mn2.8Fe0.2Si has been measured. We found that the scattering profiles were well described by two components of magnetic scattering: one of them is a normal spin-wave excitation mode with antiferromagnetic correlation that has linear dispersion relation. The other is the Gaussian-shaped mode located around the magnetic Bragg points. © 1998 Elsevier Science B.V. All rights reserved., Elsevier
Physica B: Condensed Matter, 1997年, ［査読有り］

Neutron diffraction study of C14-Laves-phase, TbMn2 and DyMn2
K. Inoue; Y. Nakamura; Y. Yamaguchi; K. Ohoyama; S. Funahashi; A. V. Tsvyashchenko; L. Fomicheva, The temperature dependence of powder neutron diffraction for hexagonal C14-Laves-phase TbMn2 and DyMn2 has been measured. Ferromagnetism and antiferromagnetism coexist in TbMn2. The ferromagnetic component continues up to 60 K, whereas the antiferromagnetic component takes its maximum value at around 55 K, begins to decrease above 55 K and vanishes at around 80 K. The magnetic unit cell of the antiferromagnetism is twice of the chemical one in an a-direction. A presumable magnetic structure has been discussed. For C14-DyMn2, no other structure is observed except for the ferromagnetic one which disappears at around 35 K., Elsevier
Physica B: Condensed Matter, 1997年

HERMES, the high-efficiency multipurpose powder diffractometer
K. Ohoyama; T. Kanouchi; K. Nemoto; M. Ohashi; T. Kajitani; Y. Yamaguchi, We have constructed the high-efficiency and medium-resolution powder diffractometer with multi-detector system, HERMES, at JRR-3M reactor at JAERI. A typical counting duration and the best resolution are 2-5 h and 0.3% Δd/d, respectively. We have obtained satisfactory results in crystal and magnetic structure refinement, and diffuse scattering measurements on a single crystal. The instrumental details and experimental performance are presented. © 1998 Elsevier Science B.V. All rights reserved., Elsevier
Physica B: Condensed Matter, 1997年

Magnetic and structural phase transition in heavy rare-earth compound DyB6
K. Takahashi; H. Nojiri; K. Ohoyama; M. Ohashi; Y. Yamaguchi; S. Kunii; M. Motokawa, We report the neutron diffraction experiment on heavy rare-earth hexaboride DyB6. The results indicate that the structural phase transition occurs at 32 K, and the antiferromagnetic order at TN = 26 K. The propagation vector of the spin structure is found to be k = 〈1/4 1/4 1/2〉 and triple-K spin structure is proposed. © 1998 Elsevier Science B.V. All rights reserved., Elsevier
Physica B: Condensed Matter, 1997年

NEUTRON-SCATTERING FROM LOW-CARRIER-DENSITY STRONGLY CORRELATED ELECTRON-SYSTEMS
M KOHGI; T OSAKABE; K OHOYAMA; T SUZUKI, The results of neutron-scattering experiments on Ce- and Yb-monopnictides with very low carrier density are discussed. The experiments on a single crystal of CeP revealed that the complex phase diagram under magnetic field comes from the interplay between the long-period ferromagnetic lattice of the Ce ions with Gamma(8) character and the antiferromagnetic ordering in the normal Gamma(7) Ce lattice. The inelastic-scattering experiments on a polycrystalline sample of YbP show the existence of strong short-range spin correlation at temperatures far above T-N The result indicates that the Kondo-like properties in Yb-monopnictides seen at low temperatures originate from anomalous spin correlations. The experimental results from CeP and YbP are discussed in relation with the magnetic polaron model., ELSEVIER SCIENCE BV
PHYSICA B, 1995年08月, ［査読有り］

[要修正]Anomalous short-range spin correlations in Yb monopnictides
K. Ohoyama; T. Osakabe; A. Dönni; M. Kohgi; A. Oyamada; T. Suzuki
Physica B: Physics of Condensed Matter, 1995年08月, ［査読有り］

ANISOTROPIC EXCHANGE INTERACTION IN CR2AS
K ISHIMOTO; M OKONOGI; K OHOYAMA; K NAKAJIMA; M OHASHI; H YAMAUCHI; Y YAMAGUCHI; S FUNAHASHI, Neutron elastic and inelastic scattering was performed on a single crystal of the antiferromagnetic compound Cr2As. The temperature dependence of the Cr(I) sublattice magnetization has a peculiar form, compared with that of Cr(II). The spin-wave dispersion relation was obtained up to the zone boundary along the [001] axis and up to 12 meV along the [100] axis. The magnon energy gap is found to obey almost the same temperature dependence as that of the Cr(I) sublattice magnetization. These results suggest that an anisotropic exchange interaction plays an important role in the magnetic behavior of Cr2As., ELSEVIER SCIENCE BV
PHYSICA B, 1995年08月, ［査読有り］

Structural Evolution of Spin-Peierls Material CuGeO[3] Studied by Neutron Scattering
Arai Masatoshi; Fujita Masaki; Ubukata Katsunori; Ohta Hitoshi; Motokawa Mitsuhiro; Otomo Toshiya; Ohoyama Kenji; Mino Michinobu; Akimitsu Jun; Fujita Osamu
Journal of Magnetism and Magnetic Materials, 1995年, ［査読有り］

NEUTRON-DIFFRACTION STUDY OF ANTIFERROMAGNETIC ORDER IN THE KONDO COMPOUND CEPDSN
H KADOWAKI; M KOHGI; K OHOYAMA; M KASAYA, Magnetic structure of the Kondo compound CePdSn is studied by neutron diffraction experiments on a single-crystalline sample. Below T(N)=7 K, Ce moments establish a single-Q type ordering S(nv)=a(v) e(ik.R(n) + a(v)* e(-ik.R(n)) with incommensurate modulation vector k=0.473b*. The polarization vectors a(v) cannot uniquely be determined from scattering intensities, and thus those which reproduce the intensities are selected using a maximum entropy method. The polarization vectors have a, b and c components with root mean square of the moment m(rms)=0.82+/-0.08 mu(B) (m(rms)a=0.59, M(rms)b=0.48, m(rms)c=0.30 mu(B)) at T = 1.5 K., PHYSICAL SOC JAPAN
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 1994年06月, ［査読有り］

Neutron Scattering Studies on Spin-Peierls Material CuGeO[3]
Arai Masatoshi; Fujita Masaki; Ubukata Katsunori; Bokui Takahiro; Tabata Kiyoshi; Ohta Hitoshi; Motokawa Mitsuhiro; Otomo Toshiya; Ohoyama Kenji; Mino Michinobu; Akimitsu Jun; Fujita Osamu
Journal of the Physical Society of Japan, 1994年, ［査読有り］

NEUTRON-SCATTERING STUDIES OF CE(ZN1-XCUX)2
T OSAKABE; M KOHGI; K OHOYAMA; T KITAI, Neutron quasi-elastic scattering studies and susceptibility measurements of Ce(Zn1-xCux)2 with x = 0, 0.1, 0.15, 0.2 and 0.25 are reported. While the Neel temperature falls rapidly with increasing x and no ordering appears around x = 0.2, the line width of the quasi-elastic scattering remains constant., ELSEVIER SCIENCE BV
PHYSICA B-CONDENSED MATTER, 1993年05月, ［査読有り］

NEUTRON-SCATTERING STUDY OF CENISN
M KOHGI; K OHOYAMA; T OSAKABE; M KASAYA; T TAKABATAKE; H FUJII, Neutron scattering studies on the gap-type Kondo system CeNiSn as well as on its reference materials CePdSn and CeptSn are reported. CeNiSn shows a Lorentzian-like broad magnetic response centered at E = 0 with an anomalous peak at about 4 meV. Well-defined crystal field excitations have been observed for CePdSn and CePtSn., ELSEVIER SCIENCE BV
PHYSICA B-CONDENSED MATTER, 1993年05月, ［査読有り］

SPIN DYNAMICS OF YBX (X = N, P, AS)
K OHOYAMA; M KOHGI; T OTOMO; T OSAKABE; A OYAMADA; T SUZUKI, The neutron quasi-elastic scattering (QES) spectra for YbX (X = N, P, As) show a quite common feature independent of X. The Kondo effect almost completely suppresses the magnetic ordering, which indicates that T(K) is comparable to T(RKKY) of about 20 K. The crossover of QES spectra from a Gaussian-like to a Lorentzian-like form occurs with the increase of temperature., ELSEVIER SCIENCE BV
PHYSICA B-CONDENSED MATTER, 1993年05月, ［査読有り］

YbNにおける異常な結晶場分裂
K. Ohoyama; M. Kohgi; T. Nakane; M. Arai; A.D. Taylor; A. Oyamada; T. Suzuki, The anomalous splitting of the GAMMA-8 excited state of YbN was studied by neutron inelastic scattering, The experimental result suggests that the anomaly arises from the magneto-clastic interaction., ELSEVIER SCIENCE BV
Physica B: Physics of Condensed Matter, 1992年06月, ［査読有り］

Magnetic properties of the dense Kondo compounds CePdSn and YbNiSn
M. Kasaya; T. Tani; K. Ohoyama; M. Kohgi; Y. Isikawa, The temperature dependence of the electrical resistivity of Ce0.2La0.8PdSn suggest that CePdSn is a dense Kondo compound. The experimental Γ value is moderately large, 60 mJ/mol K2. The magnetic structure of CePdSn determined by neutron diffraction is of a simple spiral one with the magnetic moment of (1±0.3)μB. The dense Kondo compound YbNiSn is a weak ferromagnet, which originates from the canting of antiferromagnetic sublattice within the ac-plane. © 1992.
Journal of Magnetism and Magnetic Materials, 1992年02月02日

NEUTRON-SCATTERING STUDIES OF CETSN (T = NI, PD)
M KOHGI; K OHOYAMA; T OSAKABE; M KASAYA, Neutron scattering studies on CeTSn (T = Ni, Pd) are reported. From the single-crystal diffraction experiment, the magnetic structure of CePdSn below T(N) was found to be an incommensurate one with a propagation vector of [0, 0.473, 0] and a magnetic moment of about 1-mu-B. Well-defined crystal field excitations were observed for CePdSn at 17.4 and 25.8 meV. On the other hand, the magnetic inelastic response of CeNiSn is rather structureless like a quasi-elastic scattering with a large linewidth., ELSEVIER SCIENCE BV
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 1992年02月, ［査読有り］

Ybモノプニクタイドにおける結晶場励起
M. Kohgi; K. Ohoyama; A. Oyamada; T. Suzuki; M. Arai, ELSEVIER SCIENCE BV
Physica B: Physics of Condensed Matter, 1990年04月, ［査読有り］

軽元素ドープ系材料での新しい原子イメージング法 ー白色中性子ホログラフィー ー＾
大山研司、林 好一
日本物理学会誌, 2022年06月, ［査読有り］, ［招待有り］
筆頭著者

新しい水素イメージング法への挑戦 白色中性子ホログラフィー
大山研司、林 好一
日本結晶学会誌, 2022年05月31日, ［査読有り］, ［招待有り］

J‐PARC MLFにおける偏極³He中性子スピンフィルターの開発
吉良弘; 林田洋寿; 茂吉武人; 宗像孝司; 中尾朗子; 鈴木淳市; 加倉井和久; 奥隆之; 酒井健二; 廣井孝介; 高田慎一; 大原高志; 鬼柳亮嗣; 猪野隆; 大山研司; 大河原学
日本中性子科学会年会講演概要集, 2017年

偏極中性子散乱装置POLANOにおける³He中性子スピンフィルターの開発 II
大河原学; 藤田全基; 南部雄亮; 猪野隆; 横尾哲也; 伊藤晋一; 吉良弘; 林田洋寿; 加倉井和久; 酒井健二; 廣井孝介; 奥隆之; 大山研司
日本中性子科学会年会講演概要集, 2016年

24aAD-2 マルチフェロイック物質MnWO_4の強磁場中性子回折II
鳴海 康雄; 木原 工; 大山 研司; 野尻 浩之; 春木 康平; 木村 剛
日本物理学会講演概要集, 2015年

偏極中性子散乱装置POLANOにおける³He中性子スピンフィルターの開発
大河原学; 南部雄亮; 藤田全基; 猪野隆; 横尾哲也; 伊藤晋一; 吉良弘; 林田洋寿; 酒井健二; 廣井孝介; 奥隆之; 加倉井和久; 大山研司
日本中性子科学会年会講演概要集, 2015年

Development of an in-situ spin-exchange optical pumping 3He neutron spin filter
T. Oku; H. Hayashida; H. Kira; K. Sakai; K. Hiroi; T. Shinohara; Y. Sakaguchi; T. Ino; M. Ohkawara; K. Ohoyama; L.-J. Chang; M. Nakamura; J. Suzuki; H.M. Shimizu; K. Aizawa; M. Arai; Y. Endoh; K. Kakurai
Proc. of the 21st Meeting of the International Collaboration on Advanced Neutron Sources, Sep. 29-Oct. 3, 2014, Mito, 2015年

30pAB-3 偏極散乱装置POLANOの建設状況II(30pAB 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))
横尾 哲也; 大山 研司; 伊藤 晋一; 岩佐 和晃; 金子 直勝; 大河原 学; 鈴木 純一; 室屋 孝司; 菅井 征二; 相澤 一也
日本物理学会講演概要集, 2014年03月05日

オンビームSEOP型³He中性子偏極フィルターの開発と応用
奥隆之; 林田洋寿; 酒井健二; 篠原武尚; 中村充孝; 相澤一也; 新井正敏; 遠藤康夫; 加倉井和久; 吉良弘; 坂口佳史; 鈴木淳市; 猪野隆; 平賀晴弘; 清水裕彦; 大河原学; 大山研司
物構研サイエンスフェスタ要旨集, 2014年

In‐situ SEOP方式偏極³He中性子スピンフィルターの応用と磁気シールドの開発
吉良弘; 坂口佳史; 鈴木淳市; 奥隆之; 林田洋寿; 酒井健二; 中村充孝; 新井正敏; 遠藤康夫; 加倉井和久; 有本靖; 猪野隆; 大河原学; 大山研司; 清水裕彦
物構研サイエンスフェスタ要旨集, 2014年

偏極³He中性子スピンフィルターを使った偏極中性子小角散乱デモ実験
吉良弘; 林田洋寿; 岩瀬裕希; 大石一城; 鈴木淳市; 奥隆之; 酒井健二; 廣井孝介; 高田慎一; 猪野隆; 大山研司; 大河原学; 加倉井和久; 相澤一也; 新井正敏
日本中性子科学会年会講演概要集, 2014年

大強度パルス中性子源における3He中性子スピンフィルターの実用化研究
奥隆之; 吉良弘; 林田洋寿; 酒井健二; 廣井孝介; 篠原武尚; 猪野隆; 大河原学; 大山研司; 高田慎一; 大石一城; 岩瀬裕希; 宮田登; 阿久津和宏; 坂口佳史; 武田全康; 鈴木淳市; 相澤一也; 新井正敏; 加倉井和久
日本中性子科学会誌「波紋」, 2014年

偏極散乱装置POLANOの建設状況(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))
横尾 哲也; 南部 雄亮; 大山 研司; 伊藤 晋一; 鈴木 純一; 佐藤 卓; 岩佐 和晃; 木村 宏之; 金子 直勝; 大河原 学
日本物理学会講演概要集, 2013年

オンビームSEOP型³He中性子偏極フィルターの開発と応用
奥隆之; 林田洋寿; 酒井健二; 篠原武尚; 中村充孝; 相澤隆; 新井正敏; 遠藤康夫; 加倉井和久; 吉良弘; 坂口佳史; 鈴木淳市; 猪野隆; 平賀晴弘; 清水裕彦; 大河原学; 大山研司
日本中性子科学会年会講演概要集, 2013年

In‐situ SEOP方式偏極³He中性子スピンフィルターの応用と磁気シールドの開発
吉良弘; 坂口佳史; 鈴木淳市; 奥隆之; 林田洋寿; 酒井健二; 中村充孝; 新井正敏; 遠藤康夫; 加倉井和久; 有本靖; 猪野隆; 大河原学; 大山研司; 清水裕彦
日本中性子科学会年会講演概要集, 2013年

Precision magnetic field mapping for the ³He neutron spin filter
Takashi Ino; Yasushi Arimoto; Hiroshi Kira; Yoshifumi Sakaguchi; Takenao Shinohara; Kenji Sakai; Takayuki Oku; Kazuhisa Kakurai; Kenji Ohoyama
Physics Procedia, 2013年01月01日

Magnetic Shield Design of In-situ SEOP Polarized 3He Neutron Spin Filter System
H.Kira; Y.Sakaguchi; J.Suzuki; T.Oku; M.Nakamura; M.Arai; K.Kakurai; Y.Endo; Y.Arimoto; T.Ino; H.M.Shimizu; T.Kamiyama; K.Ohoyama; H.Hiraka; K.Tsutsumi; K.Yamada; L.-J.Chang
Physics Procedia, 2013年, ［査読有り］

オンビームSEOP型³He偏極フィルター用小型レーザー光学系の開発
奥隆之; 林田洋寿; 酒井健二; 篠原武尚; 中村充孝; 新井正敏; 遠藤康夫; 加倉井和久; 吉良弘; 坂口佳史; 鈴木淳市; 有本靖; 猪野隆; 大山研司; 平賀晴弘; 清水裕彦
日本中性子科学会年会講演概要集, 2012年12月07日

In‐situ SEOP方式³He偏極フィルター用磁気シールドの設計
吉良弘; 坂口佳史; 鈴木淳市; 酒井健二; 奥隆之; 篠原武尚; 中村充孝; 新井正敏; 猪野隆; 有本靖; 林田洋寿; 加倉井和久; 遠藤康夫; 堤健之; 平賀晴弘; 大山研司; 清水裕彦; CHANG L‐J
日本中性子科学会年会講演概要集, 2012年12月07日

SEOP式偏極³He中性子スピンフィルターにおける到達³He偏極率制限因子についての考察
坂口佳史; 吉良弘; 奥隆之; 篠原武尚; 鈴木淳市; 酒井健二; 中村充孝; 鈴谷賢太郎; 相澤一也; 新井正敏; 武田全康; 遠藤康夫; 有本靖; 猪野隆; 清水裕彦; 神山崇; 大山研司; 平賀晴弘; 山田和芳; CHANG L. J; 尾原幸治; 加倉井和久
日本物理学会講演概要集, 2012年03月05日

反強磁性金属Mn₃Siの高エネルギー磁気励起に対するFe置換効果
奈良壮; CHE S. C.; 平賀晴弘; 大山研司; 山口泰男; 三木寛之; 堀金和正; 梶本亮一; 池内和彦; SUNGDAE J.; 中村充孝; 稲村泰弘; KOLESNIKOV A. I.; SAVICI A. T.; GRANROTH G. E.; RUSSELL E.; 新井正敏; 山田和芳
日本物理学会講演概要集, 2012年

25pCL-14 J-PARC偏極度解析中性子分光器計画の進展(25pCL 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; 佐藤 豊人; 佐藤 卓; 有馬 孝尚; 猪野 隆; 吉良 弘; 坂口 佳史; 奥 隆之; 有本 靖; 鈴木 淳市; 清水 裕彦; 岩佐 和晃; 武田 全康; 金子 耕士; 日野 正裕; 武藤 豪; 野尻 浩之; 横尾 哲也; 伊藤 晋一; 富安 啓輔; 松浦 直人; 平賀 晴弘; 藤田 全基; 木村 宏之
日本物理学会講演概要集, 2012年

Developments of In-Situ SEOP Polarized ³He Neutron Spin Filter in Japan
H. Kira; Y. Sakaguchi; Y. Sakaguchi; T. Oku; J. Suzuki; M. Nakamura; M. Arai; Y. Endoh; L. J. Chang; L. J. Chang; L. J. Chang; K. Kakurai; Y. Arimoto; T. Ino; H. M. Shimizu; T. Kamiyama; K. Ohoyama; H. Hiraka; K. Tsutsumi; K. Yamada
Journal of Physics: Conference Series, 2011年08月30日

偏極³He中性子スピンフィルターのガラスセルの開発 IV
坂口佳史; 吉良弘; 奥隆之; 篠原武尚; 鈴木淳市; 酒井健二; 中村充孝; 鈴谷賢太郎; 相澤一也; 新井正敏; 武田全康; 遠藤康夫; 有本靖; 猪野隆; 清水裕彦; 神山崇; 大山研司; 平賀晴弘; 山田和芳; CHANG L. J; 尾原幸治; 加倉井和久
日本物理学会講演概要集, 2011年08月24日

中性子光学及び検出システムの開発と応用:研究概要
鈴木淳市; 高田慎一; 吉良弘; 篠原武尚; 奥隆之; 中村充孝; 柴田薫; 高橋伸明; 相澤一也; 甲斐哲也; 大井元貴; 原田正英; 酒井健二; 及川健一; 前川藤夫; 曽山和彦; 新井正敏; 坂口佳史; CHANG L.J; 酒井卓郎; 松林政仁; 加倉井和久; 佐藤節夫; 武藤豪; 有本靖; 猪野隆; 清水裕彦; 大山研司; 山田和芳; PARKER J; 澤野達裁; 谷森達; 古坂道弘; 鬼柳善明; 高橋浩之; GUERARD B
日本原子力研究開発機構JAEA-Review(Web), 2011年06月

Characterization of glasses for ³He neutron spin filter cells
Y. Sakaguchi; Y. Sakaguchi; H. Kira; T. Oku; T. Shinohara; J. Suzuki; K. Sakai; M. Nakamura; K. Suzuya; M. Arai; M. Takeda; S. Wakimoto; D. Yamazaki; S. Koizumi; Y. Endoh; K. Kakurai; Y. Arimoto; T. Ino; H. M. Shimizu; T. Kamiyama; K. Ohoyama; H. Hiraka; K. Tsutsumi; K. Yamada; L. J. Chang; L. J. Chang
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011年04月01日

26aEC-7 中性子回折による単結晶YbPdの磁気構造解析(26aEC Yb系,領域8(強相関系:高温超伝導,強相関f電子系など))
杉島 正樹; 光田 暁弘; 和田 裕文; 大山 研司
日本物理学会講演概要集, 2011年03月03日

フェルミチョッパー中性子非弾性散乱装置「四季」
梶本亮一; 中村充孝; 横尾哲也; 稲村泰弘; 水野文夫; 中島健次; 高橋伸明; 河村聖子; 丸山龍治; 曽山和彦; 柴田薫; 鈴谷賢太郎; 中谷健; 佐藤節夫; 伊藤幸弘; 岩橋孝明; 神原理; 田中浩道; 吉田登; 帷子朝彦; 相澤一也; 新井正敏; 脇本秀一; 社本真一; 藤田全基; 平賀晴弘; 大山研司; 山田和芳
日本物理学会講演概要集, 2011年03月03日

Orbital Ordering of Intermediate-Spin State of Co3+ in Sr3YCo4O10.5
NAKAO Hironori; MURATA Tetsuya; BIZEN Daisuke; MURAKAMI Youichi; OHOYAMA Kenji; YAMADA Kazuyoshi; ISHIWATA Shintaro; KOBAYASHI Wataru; TERASAKI Ichiro
J Phys Soc Jpn, 2011年02月15日

22pJA-2 J-PARC偏極度解析中性子分光器計画の進展(22pJA 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; 佐藤 豊人; 佐藤 卓; 有馬 孝尚; 猪野 隆; 吉良 弘; 坂口 佳史; 奥 隆之; 有本 靖; 鈴木 淳市; 清水 裕彦; 岩佐 和晃; 武田 全康; 金子 耕士; 日野 正裕; 武藤 豪; 野尻 浩之; 横尾 哲也; 伊藤 晋一; 平賀 晴弘; 藤田 全基; 松浦 直人; 木村 宏之; 富安 啓輔
日本物理学会講演概要集, 2011年

25aTN-6 J-PARC偏極度解析中性子分光器計画の現状(25aTN 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; 佐藤 卓; 富安 啓輔; 有馬 孝尚; 猪野 隆; 吉良 弘; 坂口 佳史; 奥 隆之; 有本 靖; 鈴木 淳市; 清水 裕彦; 岩佐 和晃; 武田 全康; 金子 耕士; 日野 正裕; 武藤 豪; 野尻 浩之; 伊藤 晋一; 横尾 哲也; 平賀 晴弘; 藤田 全基; 松浦 直人; 佐藤 豊人; 堀金 和正
日本物理学会講演概要集, 2011年

中性子科学における学生教育
平賀晴弘; 岩佐和晃; 大山研司
波紋, 2011年

Application of Hot-Pressed Ge-Crystal Monochromators for Reactor-Based Neutron Beam Experiments
H. Hiraka; Y. Miyake; S.-C. Che; N. Murakami; M. Ohkawara; K. Nemoto; K. Horigane; K. Ohoyama; Y. Yamaguchi; K. Yamada
J. Phys. Soc. Jpn., 2011年, ［査読有り］

J‐PARCフェルミチョッパー型中性子分光器「四季」
梶本亮一; 中村充孝; 横尾哲也; 稲村泰弘; 水野文夫; 中島健次; 高橋伸明; 河村聖子; 丸山龍治; 曽山和彦; 柴田薫; 鈴谷賢太郎; 中谷健; 佐藤節夫; 伊藤幸弘; 岩橋孝明; 神原理; 田中浩道; 吉田登; 帷子朝彦; 相澤一也; 新井正敏; 脇本秀一; 社本真一; 藤田全基; 平賀晴弘; 大山研司; 山田和芳
日本物理学会講演概要集, 2010年08月18日

チョッパー型中性子分光器「四季」の現状
梶本亮一; 中村充孝; 横尾哲也; 稲村泰弘; 水野文夫; 中島健次; 高橋伸明; 河村聖子; 丸山龍治; 曽山和彦; 柴田薫; 鈴谷賢太郎; 中谷健; 佐藤節夫; 伊藤幸弘; 岩橋孝明; 神原理; 田中浩道; 吉田登; 相澤一也; 新井正敏; 脇本秀一; 社本真一; 藤田全基; 平賀晴弘; 大山研司; 山田和芳
日本物理学会講演概要集, 2010年03月01日

22pPSA-39 フラストレートした2等辺三角格子反強磁性体CuMnO_2の中性子散乱(22pPSA 領域3ポスターセッション(酸化物・f電子系磁性・スピングラス・量子スピン・フラストレーション系・実験技術・磁性一般),領域3(磁性,磁気共鳴))
寺田 典樹; 北澤 英明; 目時 直人; 大山 研司
日本物理学会講演概要集, 2010年

23aWP-6 金属ヘリカル磁性体MnPにおける逆Dzyaloshinsky-Moriya効果の可能性(23aWP フラストレーション系(新物質,スピングラス,その他),領域3(磁性,磁気共鳴))
山崎 照夫; 田畑 吉計; 和気 剛; 中村 裕之; 松浦 直人; 大山 研司; 横山 淳
日本物理学会講演概要集, 2010年

偏極³He中性子スピンフィルターのガラスセルの開発状況
坂口佳史; 吉良弘; 奥隆之; 篠原武尚; 鈴木淳市; 酒井健二; 中村充孝; 鈴谷賢太郎; 相澤一也; 新井正敏; 武田全康; 遠藤康夫; CHANG L.J; 有本靖; 猪野隆; 清水裕彦; 神山崇; 大山研司; 平賀晴弘; 堤健之; 山田和芳; 尾原幸治; 加倉井和久
日本中性子科学会年会講演概要集, 2010年

中性子小角散乱装置SANS‐J‐IIにおける³Heスピンフィルターを用いた偏極解析
坂口佳史; 吉良弘; 奥隆之; 篠原武尚; 鈴木淳市; 酒井健二; 中村充孝; 相澤一也; 新井正敏; 能田洋平; 小泉智; 武田全康; 遠藤康夫; CHANG L.J; 有本靖; 猪野隆; 清水裕彦; 神山崇; 大山研司; 平賀晴弘; 堤健之; 山田和芳; 加倉井和久
日本中性子科学会年会講演概要集, 2010年

フェルミチョッパー中性子分光器「四季」
梶本亮一; 中村充孝; 横尾哲也; 稲村泰弘; 水野文夫; 中島健次; 高橋伸明; 河村聖子; 丸山龍治; 曽山和彦; 柴田薫; 鈴谷賢太郎; 中谷健; 佐藤節夫; 伊藤幸弘; 岩橋孝明; 神原理; 田中浩道; 吉田登; 帷子朝彦; 相澤一也; 新井正敏; 脇本秀一; 社本真一; 藤田全基; 平賀晴弘; 大山研司; 山田和芳
日本中性子科学会年会講演概要集, 2010年

チョッパー型中性子非弾性散乱装置「四季」
梶本亮一; 横尾哲也; 中村充孝; 中島健次; 稲村泰弘; 高橋伸明; 丸山龍治; 曽山和彦; 水野文夫; 柴田薫; 鈴谷賢太郎; 中谷健; 佐藤節夫; 伊藤幸弘; 岩橋孝明; 神原理; 田中浩道; 吉田登; 相澤一也; 新井正敏; 脇本秀一; 社本真一; 藤田全基; 平賀晴弘; 大山研司; 山田和芳; 武田和雄; 仁井田浩二
日本物理学会講演概要集, 2009年03月03日

Relationship between Structure and Superconductivity in FeSe1-xTex
K. Horigane; H. Hiraka; K. Ohoyama
Journal of the Physical Society of Japan, 2009年

動き出したJ‐PARCチョッパー分光器「四季」
梶本亮一; 中村充孝; 横尾哲也; 稲村泰弘; 水野文夫; 中島健次; 高橋伸明; 河村聖子; 丸山龍治; 曽山和彦; 柴田薫; 鈴谷賢太郎; 中谷健; 佐藤節夫; 伊藤幸弘; 岩橋孝明; 神原理; 田中浩道; 吉田登; 相澤一也; 新井正敏; 脇本秀一; 社本真一; 藤田全基; 平賀晴弘; 大山研司; 山田和芳
日本中性子科学会年会講演概要集, 2009年

30aRE-8 チョッパー型中性子非弾性散乱装置「四季」(30aRE X線・粒子線(中性子),領域10(誘電体,格子欠陥,X線・粒子線,フォノン物性))
梶本 亮一; 柴田 薫; 鈴谷 賢太郎; 中谷 健; 佐藤 節夫; 伊藤 幸弘; 岩橋 孝明; 神原 理; 田中 浩道; 吉田 登; 相澤 一也; 横尾 哲也; 新井 正敏; 脇本 秀一; 社本 真一; 藤田 全基; 平賀 晴弘; 大山 研司; 山田 和芳; 武田 和雄; 仁井田 浩二; 中村 充孝; 中島 健次; 稲村 泰弘; 高橋 伸明; 丸山 龍治; 曽山 和彦; 水野 文夫
日本物理学会講演概要集, 2009年

Spin-singlet ground state in the two-dimensional frustrated triangular lattice: YbAl3C3
KATO Yoshiaki; KOSAKA Masashi; NOWATARI Hiromi; SAIGA Yuta; YAMADA Atsushi; KOBIYAMA Takuya; KATANO Susumu; OHOYAMA Kenji; SUZUKI Hiroyuki S; ASO Naofumi; IWASA Kazuaki
Journal of the Physical Society of Japan, 2008年05月15日

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
Journal of the Physical Society of Japan, 2008年04月15日

Resonance-Like Magnetic Excitations in Spinel Ferrimagnets FeCr2O4 and NiCr2O4 Observed by Neutron Scattering
K. Tomiyasu; H. Hiraka; K. Ohoyama; K. Yamada
J. Phys. Soc. Jpn., 2008年, ［査読有り］

Scanning wide-angle neutron diffraction and its application to local structures investigations in stainless steel
Kenji Ohoyama; Kazuyuki Isawa; Kazuyoshi Yamada
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS, 2007年12月

Magnetization process of tetragonal antiferromagnet, ErB2C2
Hideya Onodera; Aya Hino; Kenji Ohoyama; Elichi Matsuoka; Tsutomu Nojima
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 2007年03月

Versatility of advenced KINKEN triple-axis neutron spectrometer, AKANE
H. Hiraka; K. Ohoyama; Y. Yamaguchi; K. Yamada
J. Magn. Magn. Mat., 2007年

High Intensity Chopper Spectrometer 4SEASONS at J-PARC
R. Kajimoto; T. Yokoo; K. Nakajima; M. Nakamura; K. Soyama; T. Ino; S. Shamoto; M. Fujita; K. Ohoyama; H. Hiraka; K. Yamada; M. Arai
Journal of Neutron Research (Taylor & Francis), 2007年

Magnetic phase diagrams of Dy1-xYxB2C2 (x=0.4 and 0.5)
H Onodera; K Indoh; A Tobo; K Ohoyama
PHYSICA B-CONDENSED MATTER, 2006年05月

Magnetic structures of antiferroquadrupolar ordering compound DyB2C2 under magnetic fields
K Ohoyama; A Tobo; S Katano; H Onodera
PHYSICA B-CONDENSED MATTER, 2006年05月

東北大金研三軸型中性子分光器AKANE
平賀 晴弘; 大山 研司; 山口 泰男; 山田 和芳
波紋, 2006年

30pXD-7 多重積層放物面型熱中性子収束光学素子の集光特性(30pXD X線・粒子線(中性子・粒子線),領域10(誘電体,格子欠陥,X線・粒子線,フォノン物性))
池田 一昭; 大山 研司; 平賀 晴弘; 篠原 武尚; 広田 克也; 佐藤 広海; 清水 裕彦; 日野 正裕; 奥 隆之; 鈴木 淳市; 曽山 和彦
日本物理学会講演概要集, 2006年

Antiferromagnetic order in disorder-induced insulating phase of SrRu1-xMnxO3 (0.4 <= x <= 0.6)
M Yokoyama; C Satoh; A Saitou; H Kawanaka; H Bando; K Ohoyama; Y Nishihara
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2005年06月

Electrical resistivity and AG susceptibility in quadrupolar and magnetic ordering compounds Dy1-xYxB2C2
K Indoh; A Tobo; K Ohoyama; H Onodera
PHYSICA B-CONDENSED MATTER, 2005年04月

25aYS-2 放物面型多層膜スーパーミラーによる熱・冷中性子収束光学素子の開発(X線・粒子線(X線),領域10(誘電体, 格子欠陥, X線・粒子線, フォノン物性))
池田 一昭; 郭 建強; 鈴木 亨; 渡邉 裕; 上原 嘉宏; 林 偉民; 大森 整; 日野 正裕; 田崎 誠司; 奥 隆之; 鈴木 淳市; 安達 智宏; 曽山 和彦; 大山 研司; 平賀 晴弘; 篠原 武尚; 森嶋 隆裕; 広田 克也; 三島 賢二; 佐藤 広海; 清水 裕彦; 森田 晋也
日本物理学会講演概要集, 2005年

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; 本多 史憲; 金子 耕士; Jnen Shintar; 伊藤 晋一; 大山 研司; 岩佐 和晃; 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
日本物理学会講演概要集, 2005年

Anisotropy in Magnetic Phase Diagram of TbB₂C₂ with Field-Induced Antiferroquadrupolar Order
IDO Kaihei; TOBO Aya; KANEKO Koji; OHOYAMA Kenji; ONODERA Hideya
J. Phys. Soc. Jpn., 2005年

Characteristic profile of magnetic diffuse scattering in ErB₂C₂
K. Ohoyama; H. Kimura; Y. Noda; K. Kaneko; A. Hino; A. Tobo; H. Onodera
Physica B, 2005年

Hyperfine interactions in antiferroquadrupolar ordering compound DyB2C2 studied by Dy-161 Mossbauer spectroscopy on the Y-diluted system
K Indoh; A Tobo; K Ohoyama; H Onodera
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2004年12月

Magnetic phase diagrams of Ce1-xMxB2C2 (M = La and Lu)
A. Tobo; H. Yamauchi; E. Kishi; M. Sakata; K. Ishimoto; K. Ohoyama; H. Onodera; Y. Yamaguchi
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 2004年05月

Three dimension measurements of magnetic diffuse scattering in the rare earth compound ErB₂C₂
K. Ohoyama; H. Kimura; Y. Noda; K. Kaneko; A. Hino; A. Tobo; H. Onodera
Activity Report on Neutron Scattering Research, 2004年

Neutron structural analysis of La1-xSrxMnO3 - Variation of one-electron bandwidth W with hole doping
S Xu; Y Moritomo; K Ohoyama; A Nakamura
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2003年03月

Neutron diffraction study of shape memory effect of Ni2MnGa-type alloys
K Inoue; Y Yamaguchi; Y Noda; K Ohoyama; H Kimura; K Enami
THERMEC'2003, PTS 1-5, 2003年

29pPSA-9 TbB_2C_2 における (100) 周りの特異な磁気散乱
金子 耕司; 大山 研司; 目時 直人; 松田 雅昌; 小野寺 秀也; 山口 泰男
日本物理学会講演概要集, 2003年

31pWG-2 TbB_2C_2 の [110] 方向における磁場誘起反強四極子秩序相
金子 耕士; 目時 直人; 大山 研司; 松田 雅昌; 鈴木 淳市; 小野寺 秀也; 山口 泰男
日本物理学会講演概要集, 2003年

Unusual Magnetic Diffuse Scattering in the Tetragonal TbB₂C₂
K. Kaneko; K. Ohoyama; R. Kiyanagi; H. Kimura; Y. Noda; H. Onodera; Y. Yamaguchi
Activity Report on Neutron Scattering Research, 2003年

Neutron-diffraction study of the magnetic structure of GdB2C2
Y Yamaguchi; K Ohoyama; H Yamauchi; K Indoh; H Onodera
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 2002年12月

The oxygen dependence of the magnetic structure for Sr3Fe2O7-delta
K Mori; T Kamiyama; H Kobayashi; T Arima; K Ohoyama; S Ikeda
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 2002年12月

Anomalous antiferromagnetic properties of the tetragonal compound, TbB2C2 (vol 70, pg 3112, 2001)
K Kaneko; H Onodera; H Yamauchi; K Ohoyama; A Tobo; Y Yamaguchi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2002年12月

Antiferromagnetic order above antiferroquadrupolar transition temperature of HoB2C2
A Tobo; T Ohmori; T Matsumura; K Hirota; N Oumi; H Yamauchi; K Ohoyama; H Onodera; Y Yamaguchi
PHYSICA B-CONDENSED MATTER, 2002年03月

Phase separation and ferromagnetic transition in B-site substituted Nd1/2Ca1/2MnO3
A Machida; Y Moritomo; K Ohoyama; T Katsufuji; A Nakamura
PHYSICAL REVIEW B, 2002年02月

Anomalous Magnetic Ordering Phenomena in Tetragonal TbB2C2 Observed by Neutron Diffraction
KANEKO K; OHOYAMA K; KATANO S; MATSUDA M; ONODERA H; YAMAGUCHI Y
J. Phys. Soc. Jpn., 2002年

Microscopic Charge Separation in Tb1-xCaxMnO 3 (x ∼ 1)
Akihiko Machida; Yutaka Moritomo; Shigeo Mori; Naoki Yamamoto; Kenji Ohoyama; Eiji Nishibori; Masaki Takata; Makoto Sakata; Toshiya Otomo; Arao Nakamura
Journal of the Physical Society of Japan, 2002年01月01日

Magnetic properties of hp13 type TFe6Ge6(T = Zr, Nb, Hf) alloys
T Hori; R Nishihara; M Akimitsu; K Ohoyama; H Onodera; Y Yamaguchi; S Mitsudo; M Motokawa
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 2001年05月

Anomalous Antiferromagnetic Properties of the Tetragonal Compound, TbB2C2
KANEKO K; ONODERA H; YAMAUCHI H; OHOYAMA K; TOBO A; YAMAGUCHI Y
J. Phys. Soc. Jpn., 2001年

Estimate pulse shape functions for high resolution chopper spectrometers by means of the simulation calculation program, McStas
K. Ohoyama; M. Arai; S. Itoh; K. Kuwahara; M. Matsuda; T. Osakabe; T. Otomo; J. Suzuki
Proc. of the 15th Meeting of the International Collaboration on Advanced Neutron Sources, Nov. 6-9, 2000, Tsukuba, 2001年

Electronic phase diagram in bandwidth controlled manganites
A Machida; M Itoh; Y Moritomo; S Mori; N Yamamoto; K Ohoyama; A Nakamura
PHYSICA B-CONDENSED MATTER, 2000年06月

Magnetic properties of the Kondo compounds CeZn1-xGax
K Ohoyama; M Watanabe; H Onodera; H Miki; Y Yamaguchi
PHYSICA B, 2000年06月

Crystal and magnetic structure of conducting double perovskite Sr2FeMoO6
Yutaka Moritomo; Sheng Xu; Akihiko Machida; Takumi Akimoto; Eiji Nishibori; Masaki Takata; Makoto Sakata; Kenji Ohoyama
Journal of the Physical Society of Japan, 2000年01月01日

Interrelation between orbital polarization and magnetic structure in bilayer manganites
T Akimoto; Y Moritomo; K Ohoyama; S Okamoto; S Ishihara; S Maekawa; A Nakamura
PHYSICAL REVIEW B, 1999年06月

Layered antiferromagnetic state in (Nd1-zLaz)Sr2Mn2O7
Y Moritomo; A Nakamura; K Ohoyama; M Ohashi; K Hirota
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 1999年02月

29p-PSA-36 近藤化合物CeZn_<1-x>Ga_xの構造相転移と磁性
渡辺 基也; 大山 研司; 小野寺 秀也; 大橋 正義; 三木 寛之; 山口 泰男
日本物理学会講演概要集, 1999年

1p-PSB-18 CePt_2Sn_2 の磁気構造
佐々木 健夫; 片野 進; 大山 研二; 大橋 正義; 越前 勇次; 高畠 敏郎; 門脇 広明; 小嶋 健児; 植村 泰朋; LUKE G.M; 札本 安識; 長壁 豊隆; 小池 良浩; 目時 直人
日本物理学会講演概要集, 1998年

25a-PS-100 遷移金属化合物Mn_<3-X>Fe_XSiの高エネルギー磁気励起
三木 寛之; 大山 研司; 山田 和芳; 平賀 晴弘; 廣田 和馬; 冨吉 昇一; 山口 泰男
日本物理学会講演概要集, 1998年

25a-PS-107 Mn_<3-X>Ru_XGa(1≤χ≤2)合金の磁性
堀 富栄; 三木 寛之; 大山 研司; 山口 泰男
日本物理学会講演概要集, 1998年

26p-PSA-27 CeZn_<1-x>Ga_xの磁気秩序化と構造相転移
渡辺 基也; 大山 研司; 小野寺 秀也; 大橋 正義; 三木 寛之; 山口 泰男
日本物理学会講演概要集, 1998年

Crystalline Electric Field and Magnetic Properties of the TmCu<2>Si<2> Intermetallics
Masashi Kosaka; Hideya Onodera; Kenji Ohoyama; Masayoshi Ohashi; Yasuo Yamaguchi; Shintarou Nakamura; Terutaka Goto
J. Phys. Soc. Jpn., 1997年

NEUTRON-DIFFRACTION STUDY OF C-14-LAVES PHASE TBMN2
K INOUE; Y NAKAMURA; Y YAMAGUCHI; M OHASHI; K OHOYAMA; S FUNAHASHI; AV TSVYASHCHENKO; L FOMICHEVA
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 1995年11月

CRYSTALLOGRAPHIC AND MAGNETIC-STRUCTURE OF THE ITINERANT-ELECTRON ANTIFERROMAGNETS MN3-XTXSI (T=CR, FE)
H MIKI; K OHOYAMA; S FUNAHASHI; S TOMIYOSHI; Y YAMAGUCHI
PHYSICA B, 1995年08月

遍歴電子反強磁性体Mn₃Siのスピン波 II
三木寛之; 大山研司; 中島健次; 冨吉昇一; 山口泰男
日本物理学会講演概要集(年会), 1995年

遍歴電子反強磁性体Mn₃Siのスピン波 I
三木寛之; 大山研司; 中島健次; 冨吉昇一; 山口泰男
日本物理学会講演概要集(年会), 1994年

CROSSOVER FROM MAGNETIC TO NONMAGNETIC GROUND-STATE IN THE KONDO ALLOY SYSTEM CE(NI1-XPDX)SN
M KASAYA; T TANI; H SUZUKI; K OHOYAMA; M KOHGI
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 1991年08月

Hyperordered Structures in Materials
Koichi Hayashi; Shinji Kohara; Tomohiro Matsushita; Koji Kimura; Kenji Ohoyama; Yohei Onodera; Tomoko Sato; Shinji Kohara; Akihiko Hirata; Ayano Chiba; Shinya Hosokawa; Takehiko Ishikawa; Paul-François Paradis; Atsunobu Masuno; Ayako Nakata; Yoshitada Morikawa; Yu Takano; Takahiro Ohkubo; Satoshi Watanabe; Naoto Kitamura; Shinji Kohara; Motoki Shiga; Ippei Obayashi; Motoki Shiga; Satoshi Watanabe; Hiroki Taniguchi; Masanori Takemoto; Kenta Iyoki; Toru Wakihara; Atsunobu Masuno; Madoka Ono, 共著
Springer Singapore, 2023年11月, ［査読有り］
9789819952373

第５版 実験化学講座11 - 物質の構造III 回折　　　　　　　　　　　　　　　
大山研司, 共著
丸善出版(株)）, 2003年05月

白色中性子ホログラフィーでの高分解能多検出器系の実装による軽元素超秩序構造の観測　　　　　　　　　　　　　　　
大山研司
学術変革領域第７回成果報告会, 2023年11月17日
20240304

Neutron scattering technique with element selectivity for study of hyper-ordered structures of light elements　　　　　　　　　　　　　　　
*K. Ohoyama1; Y. Kobayashi1; Y. Tomimatsu1; K. Aizawa1; S. Kawakami1; K. Abe1; T. Kuroume1; M. Takita1; M. Harada2; Y. Inamura2; K. Oikawa2; N. Happo3; K. Hayashi4
MRM2023/IUMRS-ICA2023, 2023年12月13日, Materials Research Society of Japan (MRS-J)
20231211, 20231215

白色中性子ホログラフィーでの高分解能多検出器系の実装による軽元素超秩序構造の観測　　　　　　　　　　　　　　　
大山研司
学術変革領域第６回成果報告会, 2023年11月17日
20231117

白色中性子ホログラフィーを用いた軽元素超秩序構造研究の現状　　　　　　　　　　　　　　　
大山研司; 小林洋大; 富松優花; 會澤幸希; 川上修汰; 阿部幸樹; 黒梅智子; 滝田正勝; 原田正英A; 及川健一A; 稲村泰弘A; 八方直久B; 林 好一
日本物理学会 2023年年会, 2023年09月16日, 日本物理学会
20230916, 20230919

〔主要な業績〕白色中性子ホログラフィー：ビームライン提案への考察　　　　　　　　　　　　　　　
大山研司
日本中性子科学会第23回年会, 2023年09月14日, 日本中性子科学会
20230913, 20230914

新しい水素原子イメージング法：白色中性子ホログラフィー　　　　　　　　　　　　　　　
新学術領域：ハイドロジェノミクス 前期講演会, 2023年07月20日, 新学術領域：ハイドロジェノミクス, ［招待有り］
20230719, 20230721

J-PARCでの超秩序構造研究：白色中性子ホログラフィーの進展と計画　　　　　　　　　　　　　　　
大山研司、菅野友哉、高野元輝、星 翔太、小林洋大、富松優花、; 會澤幸希、川上修汰、八方直久A、原田正英B、及川健一B、稲村泰弘B、; 林 好一C
日本物理学会2023年春季大会, 2023年03月24日, 日本物理学会
20230322, 20230324

中性子ホログラフィーの高分解能化による超秩序構造中の軽元素挙動の観測　　　　　　　　　　　　　　　
大山研司
変革領域「超秩序構造科学」第５回成果報告会, 2023年03月14日
20230313, 20230314

物質中で孤立した水素の新しい観測法の確立：中性子ホログラフィーの応用　　　　　　　　　　　　　　　
大山研司
新学術領域研究「ハイドロジェノミクス」,最終報告会, 2022年11月23日, 新学術領域研究「ハイドロジェノミクス」
20221121, 20221123

元素選択性を持つ中性子散乱実験 ー 白色中性子ホログラフィー ー　　　　　　　　　　　　　　　
大山研司、會澤幸希、川上修汰、小林洋大; 富松優花; 菅野友哉; 高野元輝; 星 翔太; 八方直久; 原田正英; 及川健一、 稲村泰弘、 林 好一
第２２回 日本中性子科学会年会, 2022年10月28日, 日本中性子科学会
20221026, 20221028

中性子ホログラフィーの高分解能化による超秩序構造中の軽元素挙動の観測　　　　　　　　　　　　　　　
大山研司
超秩序構造科学 第４回成果発表会, 2022年10月01日, 変革領域「超秩序構造科学」
20221001, 20221002

Challenge of Novel atomic imaging for Hydrogen,White Neutron Holography　　　　　　　　　　　　　　　
大山研司
第2回ハイドロジェノミクス国際会議, 2022年05月18日
20220516, 20220519

新しい材料科学の目：白色中性子ホログラフィー　　　　　　　　　　　　　　　
大山研司
日本物理学会７６回年次大会 合同シンポジウム, 2021年03月14日, 日本物理学会, ［招待有り］
20210312, 20210315

白色中性子ホログラフィーの最近の進展と次の展開　　　　　　　　　　　　　　　
大山 研司; 杉本 和哉; 山本 隆文; 荒瀬 将太朗; 石﨑 たかと; 野田 新太; 菅野 友哉; 高野 元輝; 星 翔太; 八方 直久; 原田 正英; 及川 健一; 稲村 泰弘; 林 好一
日本中性子科学会2020年年会, 2020年11月09日
20201109, 20201109

白色中性子ホログラフィーで見るSi単結晶中の水素　　　　　　　　　　　　　　　
大山研司
量⼦ビーム連携研究センター（CIQuS）研究会 「無機材料中の⽔素の存在状態と機能発現」, 2020年08月27日, 高エネルギー加速器研究機構 量⼦ビーム連携研究センター（CIQuS）, ［招待有り］
20200827

CHALLENGE OF DETERMINATION OF HYDROGEN POSITIONS IN HYDRIDES BY WHITE NEUTRON HOLOGRAPHY　　　　　　　　　　　　　　　
K. Ohoyama; Y. Kanazawa; T. Yamamoto; S. Uechi; K. Sugimoto; S. Arase; S. Noda; T. Ishizaki; K. Hayashi; N. Happo; M. Harada; K. Oikawa; Y. Inamura; T. Sato; S. Orimo
1st Int. Symposium "Hydrogenomics" combined with 14th Int. Symposium "Hydrogen & Energy", 2020年01月06日

Novel Usages of NeutronsWhite Neutron Holography in J-PARC(招待）　　　　　　　　　　　　　　　
Kenji OHOYAMA
Materials Research Meeting 2019, 2019年12月11日, ［招待有り］
20191211

Novel Usages of Neutrons White Neutron Holography in J-PARC　　　　　　　　　　　　　　　
Kenji OHOYAMA
Materials Research Meeting 2019, 2019年12月11日, ［招待有り］

Novel Usages of Neutrons White Neutron Holography in J-PARC(招待）　　　　　　　　　　　　　　　
Kenji OHOYAMA
Materials Research Meeting 2019, 2019年12月11日, ［招待有り］

Novel Usages of NeutronsWhite Neutron Holography in J-PARC（招待講演）　　　　　　　　　　　　　　　
Kenji OHOYAMA
14th International Conference on the Structure of Non-Crystalline Materials (2019/11/3-8), 2019年11月05日, ［招待有り］
20191105

Novel Usages of Neutrons White Neutron Holography in J-PARC　　　　　　　　　　　　　　　
Kenji OHOYAMA
14th International Conference on the Structure of Non-Crystalline Materials (2019/11/3-8), 2019年11月05日, ［招待有り］

Novel Usages of Neutrons White Neutron Holography in J-PARC（招待講演）　　　　　　　　　　　　　　　
Kenji OHOYAMA
14th International Conference on the Structure of Non-Crystalline Materials (2019/11/3-8), 2019年11月05日, ［招待有り］

材料科学での中性子の新しい使い方：白色中性子ホログラフィー（招待講演）　　　　　　　　　　　　　　　
大山研司
第80回応用物理学会秋季学術講演会 放射線分科会シンポジウム「量子ビーム利用の最前線 ～医療・産業利用の現状と将来～」, 2019年09月19日, 日本応用物理学会, ［招待有り］
20190919

材料科学での中性子の新しい使い方：白色中性子ホログラフィー　　　　　　　　　　　　　　　
大山研司
第80回応用物理学会秋季学術講演会 放射線分科会シンポジウム「量子ビーム利用の最前線 ～医療・産業利用の現状と将来～」, 2019年09月19日, 日本応用物理学会, ［招待有り］

白色中性子ホログラフィーによる希土類化合物での原子構造へのドープ効果の観測　　　　　　　　　　　　　　　
大山研司、上地昇一、金澤雄輝、福本陽平、杉本和哉A、山本隆文A、八方直久B、林 好一C、原田正英D、及川健一D、稲村泰弘D、松浦 航、伊賀文俊
日本物理学会 第７４回年会 領域８, 2019年03月14日

White Neutron Holography - Determination of B Position in Mg2Si -　　　　　　　　　　　　　　　
K. Ohoyama
Workshop of Thermoelectric Materials at Ibaraki Univ., 2019年02月28日, ［招待有り］

Present Status and Future Plans of White Neutron Holography in J-PARC　　　　　　　　　　　　　　　
K. Ohoyama; Y. Fukumoto; S. Uechi; Y. Kanazawa; K. Sugimoto; T. Yamamoto; K. Hayashi; N. Happo; M. Harada; K. Oikawa; Y. Inamura
Symposium on 3D Active-site Science in London,, 2019年02月04日

J-PARC白色中性子ビームによる軽元素局所構造の観測（招待講演）　　　　　　　　　　　　　　　
大山研司
第32回日本放射光学会年会．放射光科学合同シンポジウム, 2019年01月11日, 日本放射光学会, ［招待有り］
20190111

中性子で何がみえるのか ー物質科学の視点からー　　　　　　　　　　　　　　　
大山研司
平成３０年物質科学研究会, 2018年12月14日, 中性子産業利用推進協議会

原子構造へのドープ効果の観測 --白色中性子ホログラフィーの進展--　　　　　　　　　　　　　　　
大山研司
日本中性子科学会 第１８回年会, 2018年12月04日, 日本中性子科学会

白色中性子ホログラフィーによるドープ材料の局所構造の可視化（招待講演）　　　　　　　　　　　　　　　
大山研司
日本物理学会 ２０１８年秋季大会, 2018年09月11日, 日本物理学会, ［招待有り］
20180911

Novel usage of neutron scattering: holography for observations of local atomic structures of light elements　　　　　　　　　　　　　　　
Kenji Ohoyama; Yohei Fukumoto; Shoichi Uechi; Yuki KanazawaKouichi Hayashi; Naohisa Happo; Masahide Harada; Yasuhiro Inamura; Kenichi Oikawa
The 31st European Crystallographic Meeting, ECM31, 2018年08月25日, ヨーロッパ結晶学会

Yb5Ge4の磁気構造解析　　　　　　　　　　　　　　　
福本陽平; 大山研司○; 青野美南; 町田阿弓A、沼倉凌介A、酒井俊A; 道村真司A; B; 小坂昌史A; 星川晃範C; 石垣徹
日本物理学会第７３回年次大会, 2018年03月22日, 日本物理学会

γ線エネルギー解析を用いた白色中性子ホログラフィーでの局所構造解析　　　　　　　　　　　　　　　
福本陽平、上地昇一、金澤雄輝、大山研司、林好一、八方直久、波田拓馬、木村耕治、細川伸也、原田正英、及川健一、稲村康弘、筒井一生、B. Paulus、M. Lederer、P. Wellmann
量子ビームサイエンスフェスタ2017, 2018年03月02日, 高エネルギー加速器研究機構

白色中性子ホログラフィーによるRB6 (R:希土類)の局所構造観測　　　　　　　　　　　　　　　
上地昇一、金澤雄輝、福本陽平、B. Paulus、M. Lederar、大山研司、 八方直久、林好一、木村耕治、細川伸也、波田拓馬、原田正英、 及川健一、稲村泰弘、松浦航、伊賀文俊
量子ビームサイエンスフェスタ2017, 2018年03月02日, 高エネルギー加速器研究機構

中性子ホログラフィーによるB ドープSi の局所構造の観測　　　　　　　　　　　　　　　
金澤雄輝、福本陽平、上地昇一、大山研司、M. Lederer、八方直久、 林好一、木村耕治、細川伸也、波田拓馬、原田正英、及川健一、 稲村泰弘、筒井一生
量子ビームサイエンスフェスタ2017, 2018年03月02日

中性子の新しい使い方：中性子ホログラフィーによるドーパント周りの原子配置の観測　　　　　　　　　　　　　　　
大山研司
量子ビームサイエンスフェスタ2017, 2018年03月02日, ［招待有り］

中性子の新しい使い方：ホログラフィーでの軽元素局所構造の観測（招待講演）　　　　　　　　　　　　　　　
大山研司
薄膜・多層膜の埋もれた界面のX線・中性子解析ワークショップ 2018, 2018年01月21日, ［招待有り］

Novel usage of neutrons White neutron holography for investigations of local atomic structuress（招待講演）　　　　　　　　　　　　　　　
K. Ohoyama; Y. Fukumoto; S. Uechi; Y. Kanazawa; K. Hayashia; N. Happob; K. Kimuraa; S. Hosokawac; T. Hadab; B. Paulusc; J. Stellhornc; M. Lederera; M. Haradad; Y. Inamurad; K. Oikawad; W. Matsuurae; F. Igae; K. Tsutsuif; P. Wellmanng
The 16th Korea-Japan meeting on Neutron Science, 2018年01月10日, 物性研、J-PARCセンター, ［招待有り］

Novel usage of neutrons,White neutron holography for investigations of local atomic structuress（招待講演）　　　　　　　　　　　　　　　
K. Ohoyama; Y. Fukumoto; S. Uechi; Y. Kanazawa; K. Hayashia; N. Happob; K. Kimuraa; S. Hosokawac; T. Hadab; B. Paulusc; J. Stellhornc; M. Lederera; M. Haradad; Y. Inamurad; K. Oikawad; W. Matsuurae; F. Igae; K. Tsutsuif; P. Wellmanng
The 16th Korea-Japan meeting on Neutron Science, 2018年01月10日, 物性研、J-PARCセンター, ［招待有り］

Local structure observation of Sm doped LaB6 by white neutron atomic resolution holography　　　　　　　　　　　　　　　
S. Uechi; Y. Kanazawa; Y. Fukumoto; B. Paulusa; K. Ohoyama; N. Happob; K. Hayashic; K. Kimurac; S. Hosokawaa; T. Hadab; M. Haradad; K. Oikawad; Y. Inamurad; W. Matsuurae; F. Igae
The 16th Korea-Japan meeting on Neutron Science, 2018年01月09日, 物性研、J-PARCセンター, ［招待有り］

Investigations of Local Structures by White Neutron Atomic Resolution Holography with γ-ray Energy Analysis　　　　　　　　　　　　　　　
Y. Fukumoto; S. Uechi; T. Kanazawa; K. Ohoyama; K. Hayashia; N. Happob; T. Hadab; K. Kimuraa; S. Hosokawac; M. Haradad; K. Oikawad; Y. Inamurad; K. Tsutsuie; B. Paulusc; M. Lederera,f; P. Wellmannf
The 16th Korea-Japan meeting on Neutron Science, 2018年01月09日, 物性研、J-PARCセンター, ［招待有り］

Local structure observation of Sm doped LaB6,by white neutron atomic resolution holography　　　　　　　　　　　　　　　
S. Uechi; Y. Kanazawa; Y. Fukumoto; B. Paulusa; K. Ohoyama; N. Happob; K. Hayashic; K. Kimurac; S. Hosokawaa; T. Hadab; M. Haradad; K. Oikawad; Y. Inamurad; W. Matsuurae; F. Igae
The 16th Korea-Japan meeting on Neutron Science, 2018年01月09日, 物性研、J-PARCセンター, ［招待有り］

Observation of doping effects to local atomic structures by atomic resolution holography　　　　　　　　　　　　　　　
Kenji OHOYAMA
2nd International Symposium of Quantum Beam Science at Ibaraki University, 2017年12月09日, 茨城大学量子線科学専攻、フロンテイアセンター, ［招待有り］

Local structure investigations of B doped Si by neutron atomic-resolution holography　　　　　　　　　　　　　　　
Y. Kanazawa; Y. Fukumoto; S. Uechi; K. Ohoyama; M. Lederer; N. Happo; K. Hayashi; K. Kimura; S. Hosokawa; T. Hada; M. Harada; K. Oikawa; Y. Inamura; K. Tsutsui
2nd International Symposium of Quantum Beam Science at Ibaraki University, 2017年12月09日, 茨城大学量子線科学専攻、フロンテイアセンター, ［招待有り］

Investigations of Local Structures by White Neutron Atomic Resolution Holography with γ-ray Energy Analysis　　　　　　　　　　　　　　　
Y. Fukumoto; S. Uechi; T. Kanazawa; K. Ohoyama; K. Hayashi; N. Happo; T. Hada; K. Kimura; S. Hosokawa; M. Harada; K. Oikawa; Y. Inamura; K. Tsutsui; B. Paulus; M. Lederer; P. Wellmann
2nd International Symposium of Quantum Beam Science at Ibaraki University, 2017年12月09日, 茨城大学量子線科学専攻、フロンテイアセンター, ［招待有り］

Local structure observation of Sm doped LaB6 by white neutron atomic resolution holography　　　　　　　　　　　　　　　
S. Uechi; Y. Kanazawa; Y. Fukumoto; B. Paulus; K. Ohoyama; N. Happo; K. Hayashi; K. Kimura; S. Hosokawa; T. Hada; M. Harada; K. Kimura; S. Hosokawa; M. Harada; K. Oikawa; Y. Inamura; K. Tsutsui; B. Paulus; M. Lederer; P. Wellmann
2nd International Symposium of Quantum Beam Science at Ibaraki University, 2017年12月09日, 茨城大学量子線科学専攻、フロンテイアセンター, ［招待有り］

Local structure investigations of B doped Si by ,neutron atomic-resolution holography　　　　　　　　　　　　　　　
Y. Kanazawa1; Y. Fukumoto1; S. Uechi1; K. Ohoyama1; M. Lederer2; N. Happo3; K. Hayashi4; K. Kimura4; S. Hosokawa5; T. Hada3; M. Harada6; K. Oikawa6; Y. Inamura6; K. Tsutsui7
2nd International Symposium of Quantum Beam Science at Ibaraki University, 2017年12月09日, 茨城大学量子線科学専攻、フロンテイアセンター, ［招待有り］

Local structure observation of Sm doped LaB6,by white neutron atomic resolution holography　　　　　　　　　　　　　　　
S. Uechi1; Y. Kanazawa1; Y. Fukumoto1; B. Paulus2; K. Ohoyama1; N. Happo3; K. Hayashi4; K. Kimura4; S. Hosokawa2; T. Hada3; M. Harada5; K. Kimura2; S. Hosokawa4; M. Harada5; K. Oikawa5; Y. Inamura5; K. Tsutsui6; B. Paulus4; M. Lederer7; P. Wellmann7
2nd International Symposium of Quantum Beam Science at Ibaraki University, 2017年12月09日, 茨城大学量子線科学専攻、フロンテイアセンター, ［招待有り］

局所構造理解の新手法：白色中性子ホログラフィーの進展　　　　　　　　　　　　　　　
大山研司1; 福本陽平1; 上地昇一2; 金澤雄輝2; 林好一3; 八方直久4; 木村耕治3; 細川伸也5; 波田拓馬4; 原田正英6; 稲村泰弘6; 筒井一生7
日本中性子科学会 年会, 2017年12月02日, 日本中性子科学会

白色中性子ホログラフィーによるSmドープLaB6の局所構造観測　　　　　　　　　　　　　　　
上地昇一1、金澤雄輝1、福本陽平1、B.Paulus4、大山研司1、; 八方直久3、林好一2、原田正英5、稲村泰弘5、松浦航1、伊賀文俊1
第１７回日本中性子科学会年会, 2017年12月02日, 中性子科学会

中性子ホログラフィーによるBドープSiの局所構造解明　　　　　　　　　　　　　　　
金澤雄輝1、福本陽平1、上地昇一1、大山研司1、M.Lederer2、林好一3、八方直久4、木村耕治3、細川伸也5、波田拓馬4、原田正英6、稲村泰弘6、筒井一生7
第１７回日本中性子科学会年会, 2017年12月02日, 中性子科学会

多波長中性子ホログラフィー法による軽元素局所構造解析　　　　　　　　　　　　　　　
福本陽平1、上地昇一1、金沢雄輝1、B. Paulus4、大山研司1、林好一2、八方直久3、木村耕治2、細川伸也4、波田拓馬3、原田正英5、稲村泰弘5、筒井一生6、P. Wellmann
第１７回日本中性子科学会年会, 2017年12月02日, 中性子科学会

中性子の新しい使い方 ーー中性子ホログラフィーでの局所構造観測　　　　　　　　　　　　　　　
大山研司
J-PARC装置勉強会, 2017年09月29日, ［招待有り］

中性子ホログラフィーによるBドープSiの局所構造解明　　　　　　　　　　　　　　　
大山研司、林好一、八方直久、木村耕治、細川伸也、波田拓馬、青野美南、福本陽平、原田正英、稲村泰弘、筒井一生
東京大学物性研究所 短期研究会, 2016年12月20日, 東京大学物性研究所 、科研費新学術領域「3D活性サイト科学」「原子層科学」

中性子ホログラフィーによるBドープSiの局所構造解明　　　　　　　　　　　　　　　
大山研司、林好一、八方直久、木村耕治、細川伸也、波田拓馬、原田正英、稲村泰弘、筒井一生
第１６回 日本中性子科学会年会, 2016年12月02日, 日本中性子科学会

中性子ホログラフィー法によるドープ系機能性材料での局所構造研究　　　　　　　　　　　　　　　
大山研司
平成28年度物質科学研究会, 2016年09月29日, 中性子産業利用推進協議会, ［招待有り］

Progress of neutron atomic resolution holography for observations of light elements(Invited talk)　　　　　　　　　　　　　　　
K. Ohoyama
International Symposium on Advanced Materials Having Multi-Degrees-of-Freedom - Optical Properties, Structural Analysis, Imaging and Informatics of Materials - (2-3 November 2015, Kumamoto), 2015年11月02日, ［招待有り］

Progress of Local Structure Investigations by Atomic Resolution Neutron Holography in Japan　　　　　　　　　　　　　　　
K. Ohoyama; K. Hayashi; S. Orimo; H. Takahashi; K. Shibata
588. WE-Heraeus Seminar Element Specific Structure Determination in Materials on Nanometer and Sub-Nanometer Scales using modern X-Ray and Neutron Techniques, 2015年04月28日, WE-Heraeus Fundation

2001年04月, 日本中性子科学会

1986年04月, 物理学会

白色中性子ホログラフィーでの高分解能多検出器系の実装による軽元素超秩序構造の観測　　　　　　　　　　　　　　　
科学研究費補助金 学術変革領域研究(A)「超秩序構造科学」公募研究
2023年04月 - 2025年03月

新しい原子イメージング法を用いたカゴ状構造内ドーパントの孤立振動の定量評価　　　　　　　　　　　　　　　
基盤研究(B)
2021年04月 - 2024年03月

超軽元素・磁気構造イメージングに向けた多波長中性子ホログラフィーの開発と応用
基盤研究（A）
名古屋工業大学
2019年04月 - 2024年03月

中性子ホログラフィーの高分解能化による超秩序構造中の軽元素挙動の観測　　　　　　　　　　　　　　　
変革領域「超秩序構造」公募研究
2021年09月 - 2023年03月

物質中で孤立した水素の新しい観測法の確立：中性子ホログラフィーの応用　　　　　　　　　　　　　　　
新学術領域 公募研究
2021年04月 - 2023年03月

軽元素制御による高機能な準安定シリコン系多元混晶材料の創製　　　　　　　　　　　　　　　
基盤研究(A)
2020年04月 - 2023年03月

水素吸蔵物質での水素位置確定法：粉末中性子ホログラフィーの実現　　　　　　　　　　　　　　　
2019年04月 - 2021年03月

エネルギー解析白色中性子ホログラフィー法の開発とドープ系機能性材料への応用　　　　　　　　　　　　　　　
基盤研究(C)
2017年04月 - 2020年03月

3Ｄ活性サイト科学のプラットフォーム構築による総括と研究支援　　　　　　　　　　　　　　　
新学術領域研究(研究領域提案型)
2014年07月 - 2019年03月

蛍光X線・中性子線ホログラフィーによるドープ原子３Dイメージング　　　　　　　　　　　　　　　
新学術領域研究(研究領域提案型)
2014年07月 - 2019年03月

特願2007-301728, 「中性子回折装置」

茨城大学KEK-Days　　　　　　　　　　　　　　　
企画立案・運営等
2022年12月27日 - 2022年12月28日