Sep. 2023, 2023年春季 第70回応用物理学会 第19回英語講演奨励賞, Observation of large anomalous Nernst effect and quantum-critical scaling in the Weyl ferromagnet Co2MnGa thin films, Professional Group of Spintronics, The Japan Society of Applied Physics
Ryota Uesugi

Observation of Omnidirectional Exchange Bias at All‐Antiferromagnetic Polycrystalline Heterointerface
Mihiro Asakura; Tomoya Higo; Takumi Matsuo; Ryota Uesugi; Daisuke Nishio‐Hamane; Satoru Nakatsuji
Advanced Materials, Jul. 2024

Large spontaneous magneto-thermoelectric effect in epitaxial thin films of the topological kagome ferromagnet Fe3Sn
Shun'ichiro Kurosawa; Tomoya Higo; Shota Saito; Ryota Uesugi; Satoru Nakatsuji
Physical Review Materials, 28 May 2024

Observation of Cluster Magnetic Octupole Domains in the Antiferromagnetic Weyl Semimetal Mn3Sn Nanowire
Hironari Isshiki; Nico Budai; Ayuko Kobayashi; Ryota Uesugi; Tomoya Higo; Satoru Nakatsuji; YoshiChika Otani
Physical Review Letters, 23 May 2024

Anisotropic anomalous transport in the kagome-based topological antiferromagnetic Mn3Ga epitaxial thin films
M. Raju; Ralph Romero; Daisuke Nishio-Hamane; Ryota Uesugi; Mihiro Asakura; Zhenisbek Tagay; Tomoya Higo; N. P. Armitage; Collin Broholm; Satoru Nakatsuji
Physical Review Materials, 26 Jan. 2024

Giant anomalous Nernst effect in polycrystalline thin films of the Weyl ferromagnet Co2MnGa
Ryota Uesugi; Tomoya Higo; Satoru Nakatsuji
Applied Physics Letters, 18 Dec. 2023

Roll‐to‐Roll Printing of Anomalous Nernst Thermopile for Direct Sensing of Perpendicular Heat Flux
Hirokazu Tanaka; Tomoya Higo; Ryota Uesugi; Kazuto Yamagata; Yosuke Nakanishi; Hironobu Machinaga; Satoru Nakatsuji, Abstract

The anomalous Nernst effect (ANE) converts heat flux perpendicular to the plane into electricity, in sharp contrast with the Seebeck effect (SE), enabling mass production, large area, and flexibility of their devices through ordinary thin‐film fabrication techniques. Heat flux sensors, one of the most promising applications of ANE, are powerful devices for evaluating heat flow and can lead to energy savings through efficient thermal management. In reality, however, SE caused by the in‐plane heat flux is always superimposed on the measurement signal, making it difficult to evaluate the perpendicular heat flux. Here, ANE‐type heat flux sensors that selectively detect a perpendicular heat flux are fabricated by adjusting the net Seebeck coefficient in their thermopile circuit with mass‐producible roll‐to‐roll sputtering methods. The direct sensing of perpendicular heat flux using ANE‐based flexible thermopiles, as well as their simple fabrication process, paves the way for the practical application of thin‐film thermoelectric devices., Wiley
Advanced Materials, 24 Jul. 2023

Magnetic imaging by the anomalous Nernst effect using atomic force microscopy
Nico Budai; Hironari Isshiki; Ryota Uesugi; Zheng Zhu; Tomoya Higo; Satoru Nakatsuji; YoshiChika Otani, IEEE
2023 IEEE International Magnetic Conference - Short Papers (INTERMAG Short Papers), May 2023

High-resolution magnetic imaging by mapping the locally induced anomalous Nernst effect using atomic force microscopy
Nico Budai; Hironari Isshiki; Ryota Uesugi; Zheng Zhu; Tomoya Higo; Satoru Nakatsuji; YoshiChika Otani
Applied Physics Letters, 06 Mar. 2023

Determination of spin Hall angle in the Weyl ferromagnet Co2MnGa by taking into account the thermoelectric contributions
Hironari Isshiki; Zheng Zhu; Hayato Mizuno; Ryota Uesugi; Tomoya Higo; Satoru Nakatsuji; YoshiChika Otani, American Physical Society (APS)
Physical Review Materials, 29 Aug. 2022

Omnidirectional Control of Large Electrical Output in a Topological Antiferromagnet
Tomoya Higo; Yufan Li; Kouta Kondou; Danru Qu; Muhammad Ikhlas; Ryota Uesugi; Daisuke Nishio‐Hamane; C. L. Chien; YoshiChika Otani; Satoru Nakatsuji, Abstract

Control of magnetization direction is essential for the wide application of ferromagnets; it defines the signal size of memory and sensor. However, the magnetization itself causes a dilemma. While its size matters to obtain strong responses upon its reversal, the large magnetization concomitantly suppresses the range of its directional control because of the demagnetizing field. On the other hand, realization of the desired magnetic anisotropy requires careful engineering of crystalline and interfacial effects to overcome the demagnetization barrier. Thus, it would be ideal if one could find alternative magnets that carry no magnetization but strong responses. The discovery of a topological metallic state in the antiferromagnet Mn₃Sn is significant; they host a large Berry curvature in momentum space, enabling the observation of disproportionately large transverse responses such as anomalous Hall and Nernst effects, the key functionalities for replacing ferromagnets in the magnetic devices. Here, the experimental realization of omnidirectional control of the large responses in an antiferromagnet is reported. In particular, it is demonstrated that the absence of shape anisotropy enables the omnidirectional control, and lifts the shape constraint in designing the magnetic devices. This work lays the technological foundation for developing simple‐structured high‐performance devices including multi‐level memory and heat flux sensor., Wiley
Advanced Functional Materials, 25 Feb. 2021

Electrical fluctuation spectra due to characteristic thermal diffusion in Ta thin films deposited by RF-magnetron sputtering
Ryota Uesugi; Takashi Komine; Masaomi Mizuno; Ryo Ando; Hideo Akabane, IOP Publishing
Japanese Journal of Applied Physics, 01 Feb. 2020

Observation of the giant anomalous Nernst effect in the Weyl ferromagnet Co2MnGa polycrystalline films　　　　　　　　　　　　　　　
Ryota Uesugi; Tomoya Higo; Satoru Nakatsuji
The 85th JSAP Autumn Meeting, 20 Sep. 2024
20240916, 20240920

Large anomalous Nernst effect in polycrystalline thin films of the Weyl ferromagnet Co2MnGa　　　　　　　　　　　　　　　
Ryota Uesugi; Tomoya Higo; Satoru Nakatsuji
APS March Meeting 2024, 04 Mar. 2024
20240303, 20240308

Giant anomalous Nernst effect in the epitaxial and polycrystalline films of the Weyl ferromagnet Co2MnGa　　　　　　　　　　　　　　　
Ryota Uesugi; Tomoya Higo; Satoru Nakatsuji
International Symposium on Quantum Electronics 2024, 14 Feb. 2024
20240213, 20240216

Atomic ordering dependence of transverse thermoelectric response due to topological electronic structure in thin film of the Weyl ferromagnet Co2MnGa　　　　　　　　　　　　　　　
Ryota Uesugi; Tomoya Higo; Susumu Minami; Daisuke Nishio-Hamane; Zheng Zhu; Mihiro Asakura; Akito Sakai; Yoshichika Otani; Ryotaro Arita; Satoru Nakatsuji
The Physical Society of Japan 2023 Annual Meeting, 17 Sep. 2023
20230916, 20230919

Logarithmic temperature dependence of transverse thermoelectric transport in the Weyl ferromagnet Co2MnGa thin film　　　　　　　　　　　　　　　
Ryota Uesugi; Tomoya Higo; Susumu Minami; Daisuke Nishio-Hamane; Zheng Zhu; Mihiro Asakura; Akito Sakai; Yoshichika Otani; Ryotaro Arita; Satoru Nakatsuji
11th International Symposium on Metallic Multilayers, 25 Jul. 2023
20230724, 20230728

Observation of large anomalous Nernst effect and quantum-critical scaling in thin films of the Weyl ferromagnet Co2MnGa　　　　　　　　　　　　　　　
Ryota Uesugi; Tomoya Higo; Susumu Minami; Daisuke Nishio-Hamane; Zheng Zhu; Mihiro Asakura; Akito Sakai; Yoshichika Otani; Ryotaro Arita; Satoru Nakatsuji
Spin-RNJ Symposium 2022, 20 Mar. 2023
20230320, 20230321

〔Major achievements〕Observation of large anomalous Nernst effect and quantum-critical scaling in the Weyl ferromagnet Co2MnGa thin films　　　　　　　　　　　　　　　
Ryota Uesugi; Tomoya Higo; Susumu Minami; Daisuke Nishio-Hamane; Zheng Zhu; Mihiro Asakura; Akito Sakai; Yoshichika Otani; Ryotaro Arita; Satoru Nakatsuji
The 70th JSAP Spring Meeting, 17 Mar. 2023
20230315, 20230318

Atomic ordering dependence of anomalous Nernst effect in thin films ofthe Weyl magnet Co2MnGa　　　　　　　　　　　　　　　
Ryota Uesugi; Tomoya Higo; Satoru Nakatsuji
2nd International Symposium on Trans-Scale Quantum Science (TSQS2022), 08 Nov. 2022
20221108, 20221111

Composition dependence of anomalous Nernst effect in the Weyl magnetic material Co2MnGa thin film　　　　　　　　　　　　　　　
Ryota Uesugi; Tomoya Higo; Zheng Zhu; Mihiro Asakura; Akito Sakai; Daisuke Nishio-Hamane; Yoshichika Otani; Satroru Nakatsuji
The 15th Asia Pacific Physics Conference, 26 Aug. 2022
20220821, 20220826

Transverse thermoelectric effect in Weyl magnetic material Co2MnGa thin film　　　　　　　　　　　　　　　
R. Uesugi; T. Higo; S. Nakatsuji
第１３回 低温科学研究センター研究交流会, 09 Mar. 2022
20220309, 20220309

Anomalous Nernst effect under in- and out-of-plane heat flux in the Weyl ferromagnet Co2MnGa thin films　　　　　　　　　　　　　　　
R. Uesugi; T. Higo; Z. Zhu; K. Kondou; A. Sakai; M. Asakura; Y. Otani; S. Nakatsuji
The 81th JSAP Autumn Meeting, 08 Sep. 2020
20200908, 20200911

Phase dependence of anomalous Nernst effect in full-Heusler alloy Co2MnGa　　　　　　　　　　　　　　　
R. Uesugi; T. Higo; Z. Zhu; K. Kondou; Y. Otani; S. Nakatsuji
The 67th JSAP Spring Meeting, 13 Mar. 2020
20200312, 20200315

Strain-induced 1/f noise of electrical resistivity in Ta thin films deposited by RF-magnetron sputtering　　　　　　　　　　　　　　　
R. Uesugi; T. Komine; M. Mizuno; R. Ando; H. Akabane
The 66th JSAP Spring Meeting, 10 Mar. 2019
20190309, 20190312

Jun. 2023 - Present, The Physical Society of Japan

Jan. 2019 - Present, The Japan Society of Applied Physics