Keisuke Tomiyasu

Profile Information

Degree: 博士（理学）

J-GLOBAL ID: 200901076058362705
researchmap Member ID: 5000033374

Research Interests

Research Areas

Natural sciences / Magnetism, superconductivity, and strongly correlated systems /

Papers

Observation of topological <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="double-struck">Z</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> vortex fluctuations in the frustrated Heisenberg magnet <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">NaCrO</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>

K. Tomiyasu, Y. P. Mizuta, M. Matsuura, K. Aoyama, H. Kawamura

Physical Review B, 106(5), Aug 2, 2022
Spin Dynamics Simulation of the Z2-vortex Fluctuations

Yo P. Mizuta, Kazushi Aoyama, Keisuke Tomiyasu, Masato Matsuura, Hikaru Kawamura

Journal of the Physical Society of Japan, 91(3), Mar 15, 2022
THz ESR Study of Peculiar Co Pyrochlore System GeCo2O4 Using Pulsed High Magnetic Field

Susumu Okubo, Hitoshi Ohta, Tatsuya Ijima, Tatsuya Yamazaki, Wei-min Zhang, Shigeo Hara, Shinichi Ikeda, Hiroyuki Oshima, Miwako Takahashi, Keisuke Tomiyasu …

Applied Magnetic Resonance, 52(4) 411-424, Apr, 2021
Damping of spinful excitons in LaCoO3 by thermal fluctuations: Theory and experiment

Atsushi Hariki, Ru-Pan Wang, Andrii Sotnikov, Keisuke Tomiyasu, Davide Betto, Nicholas B. Brookes, Yohei Uemura, Mahnaz Ghiasi, Frank M. F. de Groot, Jan Kuneš

Physical Review B, 101(24), Jun 26, 2020
Emergent spin-1 Haldane gap and ferroelectricity in a frustrated spin-12 ladder

H. Ueda, S. Onoda, Y. Yamaguchi, T. Kimura, D. Yoshizawa, T. Morioka, M. Hagiwara, M. Hagihala, M. Soda, T. Masuda …

Physical Review B, 101(14) 1-16, Apr, 2020 Peer-reviewed
A new mathematical approach to finding global solutions of the magnetic structure determination problem

K. Tomiyasu, R. Oishi-Tomiyasu, M. Matsuda, K. Matsuhira

Scientific Reports, 8(1), Dec 1, 2018 Peer-reviewed
Quantum Paramagnet Near Spin-State Transition

Keisuke Tomiyasu, Naoko Ito, Ryuji Okazaki, Yuki Takahashi, Mitsugi Onodera, Kazuaki Iwasa, Tsutomu Nojima, Takuya Aoyama, Kenya Ohgushi, Yoshihisa Ishikawa …

Advanced Quantum Technologies, 1(3) 1800057-1800057, Oct, 2018 Peer-reviewed
Cluster-Based Haldane State in an Edge-Shared Tetrahedral Spin-Cluster Chain: Fedotovite K2Cu3 O (SO4)3

M. Fujihala, T. Sugimoto, T. Tohyama, S. Mitsuda, R. A. Mole, D. H. Yu, S. Yano, Y. Inagaki, H. Morodomi, T. Kawae …

Physical Review Letters, 120(7), Feb 12, 2018 Peer-reviewed
Magnetic Properties of One-Dimensional Quantum Spin System Rb2Cu2Mo3O12 Studied by Muon Spin Relaxation

Seiko Ohira-Kawamura, Keisuke Tomiyasu, Akihiro Koda, Dita P. Sari, Retno Asih, Sungwon Yoon, Isao Watanabe, Kenji Nakajima

Proceedings of the 14th International Conference on Muon Spin Rotation, Relaxation and Resonance (μSR2017), Feb, 2018 Peer-reviewed
Excitonic dispersion of the intermediate spin state in LaCoO3 revealed by resonant inelastic x-ray scattering

Wang R.-P, Hariki A, Sotnikov A, Frati F, Okamoto J, Huang H.-Y, Singh A, Huang D.-J, Tomiyasu K, Du C.-H …

Physical Review B, 98(3), 2018 Peer-reviewed
Chiral-crystal-structure transformations and magnetic states of R3Rh4Sn13 (R= la and Ce)

Suyama K, Iwasa K, Otomo Y, Tomiyasu K, Sagayama H, Sagayama R, Nakao H, Kumai R, Kitajima Y, Damay F …

Physical Review B, 97(23), 2018 Peer-reviewed
Emergence of spin-orbit order in the spinel CuCr₂O₄

K. Tomiyasu, S. Lee, H. Ishibashi, Y. Takahashi, T. Kawamata, Y. Koike, T. Nojima, S. Torii, T. Kamiyama

submitted to Phys. Rev. Lett., 2018 Peer-reviewed
Possible Tomonaga-Luttinger spin liquid state in the spin-1/2 inequilateral diamond-chain compound K3Cu3AlO2(SO4)(4)

Masayoshi Fujihala, Hiroko Koorikawa, Setsuo Mitsuda, Katsuhiro Morita, Takami Tohyama, Keisuke Tomiyasu, Akihiro Koda, Hirotaka Okabe, Shinichi Itoh, Tetsuya Yokoo …

SCIENTIFIC REPORTS, 7(1), Dec, 2017 Peer-reviewed
Coulomb Correlations Intertwined with Spin and Orbital Excitations in LaCoO3

K. Tomiyasu, J. Okamoto, H. Y. Huang, Z. Y. Chen, E. P. Sinaga, W. B. Wu, Y. Y. Chu, A. Singh, R. -P. Wang, F. M. F. de Groot …

PHYSICAL REVIEW LETTERS, 119(19), Nov, 2017 Peer-reviewed
Small crystal distortion and long-range antiferro-orbital ordering in the spinel oxide CoV2O4

H. Ishibashi, S. Shimono, K. Tomiyasu, S. Lee, S. Kawaguchi, H. Iwane, H. Nakao, S. Torii, T. Kamiyama, Y. Kubota

PHYSICAL REVIEW B, 96(14), Oct, 2017 Peer-reviewed
Magnetic Properties of Electron-Doped LaCoO3

Keisuke Tomiyasu, Mika Sato, Shun-Ichi Koyama, Tsutomu Nojima, Ryoichi Kajimoto, Sungdae Ji, Kazuaki Iwasa

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 86(9), Sep, 2017 Peer-reviewed
Crystal-electric-field excitations and spin dynamics in Ce3Co4Sn13 semimetallic chiral-lattice phase

Kazuaki Iwasa, Yuka Otomo, Kazuya Suyama, Keisuke Tomiyasu, Seiko Ohira-Kawamura, Kenji Nakajima, Jean-Michel Mignot

PHYSICAL REVIEW B, 95(19), May, 2017 Peer-reviewed
THz ESR study of Spinel Compound GeCo2O4

Susumu Okubo, Hitoshi Ohta, Tatsuya Ijima, Tatsuya Yamasaki, Weimin Zhang, Shigeo Hara, Shinichi Ikeda, Hiroyuki Oshima, Miwako Takahashi, Keisuke Tomiyasu …

ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS, 231(4) 827-837, Apr, 2017 Peer-reviewed
Structural analysis and spin state transition in cobalt oxide Sr0.75Y0.25CoO3-delta

Shimono Seiya, Ishibashi Hiroki, Kawaguchi Shogo, Tomiyasu Keisuke, Kubota Yoshiki

ACTA CRYSTALLOGRAPHICA A-FOUNDATION AND ADVANCES, 73 C219-C219, 2017 Peer-reviewed
Phonons and stability of infinite-layer iron oxides SrFeO2 and CaFeO2

M. K. Gupta, R. Mittal, S. L. Chaplot, Cedric Tassel, Hiroshi Kageyama, K. Tomiyasu, Jon Taylor

SOLID STATE COMMUNICATIONS, 241 43-55, Sep, 2016 Peer-reviewed

Misc.

Emergent spin-$1$ Haldane gap and ferroelectricity in a frustrated spin-$1/2$ ladder

Hiroshi Ueda, Shigeki Onoda, Yasuhiro Yamaguchi, Tsuyoshi Kimura, Daichi Yoshizawa, Toshiaki Morioka, Masayuki Hagiwara, Masato Hagihala, Minoru Soda, Takatsugu Masuda …

Mar 20, 2018
スピネル酸化物CoV₂O₄の微小な格子歪みと長距離軌道秩序

石橋広記, 下野聖矢, 富安啓輔, LEE Sanghyun, 河口彰吾, 岩根啓樹, 中尾裕則, 鳥居周輝, 神山崇, 神山崇 …

日本結晶学会年会講演要旨集, 2017 83, Nov 23, 2017
Spin state transition and crystal structure in perovskite oxide Sr_0.75Y_0.25CoO_3-δusing synchrotron powder diffraction

Shimono S, Ishibashi H, Kawaguchi S, Tomiyasu K, Kubota Y

Meeting Abstracts of the Physical Society of Japan, 72 2252-2252, 2017
超高分解能粉末中性子回折によるスピネル酸化物CoV₂O₄の格子歪みの観測

石橋広記, 下野聖矢, 富安啓輔, LEE Sanghyun, 河口彰吾, 岩根啓樹, 鳥居周輝, 神山崇, 久保田佳基

物構研サイエンスフェスタ要旨集, 3rd 40, 2015
24aPS-77 Super high resolution neutron powder diffraction on vanadium spinel oxide CoV_2O_4

Ishibashi H, Shimono S, Tomiyasu K, Lee S, Kawaguchi S, Iwane H, Torii S, Kamiyama T, Kubota Y

Meeting Abstracts of the Physical Society of Japan, 70 2428-2428, 2015
9aBJ-9 X-ray and neutron scattering study on single crystals of R_3Co_4Sn_<13> (R = Ce, La)

Otomo Y., Iwasa K., Tomiyasu K., Ohira-Kawamura S., Nakajima K., Sagayama R., Nakao H., Kumai R., Murakami Y.

Meeting abstracts of the Physical Society of Japan, 69(2) 403-403, Aug 22, 2014
9pBC-4 Inelastic neutron scattering study of spin-orbit fluctuations in frustrated heavy-fermion metal LiV_2O_4

Tomiyasu K., Iwasa K., Ueda H., Niitaka S., Takagi H., Ohira-Kawamura S., Kikuchi T., Nakajima K., Yamada K.

Meeting abstracts of the Physical Society of Japan, 69(2) 306-306, Aug 22, 2014
27aCM-10 Light impurity substitution effect in EuCoO_3

Tomiyasu K., Nara S., Yagi H., Iwasa K.

Meeting abstracts of the Physical Society of Japan, 69(1) 552-552, Mar 5, 2014
28aPS-129 New Imcommensurate Magnetic Phase in MnCr_2O_4

Kousaka Y., Yoshii T., Tomiyasu K., Kumai R., Yamasaki Y., Nakao H., Campo J., Andre G., Akimitsu J.

Meeting abstracts of the Physical Society of Japan, 69(1) 622-622, Mar 5, 2014
Diffuse Scattering in the Triangular-Lattice Antiferromagnet CuCrO_2

Kajimoto R., Nakajima K., Ohira-Kawamura S., Inamura Y., Okuda T., Tomiyasu K.

Meeting abstracts of the Physical Society of Japan, 68(2) 359-359, Aug 26, 2013
26aXZB-2 Progress of Polarisation Analysis Neutron Spectrometer Project in J-PARC

Ohoyama K., Ino T., Hiraka H., Matsuura M., Fujita M., Tomiyasu K., Kimura H., Suzuki J., Shimizu H. M., Arima T. …

Meeting Abstracts of the Physical Society of Japan, 68 146-146, 2013
21aPSB-13 Search for electron-doped LaCoO_3 system and its evaluation by magnetization and resistivity measurements

Koyama S., Watahiki M., Iwasa K., Nakao H., Tomiyasu K.

Meeting abstracts of the Physical Society of Japan, 67(2) 589-589, Aug 24, 2012
19pFE-2 Spin-state polarons in lightly Co-site-impurity-doped LaCoO_3 system studied by single-crystal magnetization and fluorescence measurements

Tomiyasu K., Kubota Y., Shimomura S., Nakao H.

Meeting abstracts of the Physical Society of Japan, 67(2) 481-481, Aug 24, 2012
25pYD-5 Spin Molecules : Novel Magnetic Excitations in Frustrated Lattice

TOMIYASU Keisuke

Meeting abstracts of the Physical Society of Japan, 67(1) 641-641, Mar 5, 2012
27aYC-5 A neutron scattering study on a localized and an itinerant nature related to f^2 electron states of PrCu_4t (T=Au and Ag)

Kobayashi H., Saito K., Tomiyasu K., Iwasa K., Kawana D., Zhang S., Ishikawa Y., Mignot J. -M., Andre G, Kolesnikov A. I. …

Meeting abstracts of the Physical Society of Japan, 67(1) 684-684, Mar 5, 2012
25aPS-55 Magnetic and transport properties in light electron doped LaCoO_3

Watahiki M., Tomiyasu K., Iwasa K., Nakao H.

Meeting abstracts of the Physical Society of Japan, 67(1) 605-605, Mar 5, 2012
22pGH-4 ESR measurements of single crystal spinel compound GeCo_2O_4 II

Yamasaki T., Okubo S., Ohta H., Sakurai T., Ikeda S., Oshima H., Takahashi M., Hara S., Tomiyasu K., Watanabe T.

Meeting abstracts of the Physical Society of Japan, 66(2) 429-429, Aug 24, 2011
22aPS-57 Magnetization measurements of LaCoO_3 with diluted impurity

Kubota Y., Tomiyasu K., Iwasa K.

Meeting abstracts of the Physical Society of Japan, 66(2) 522-522, Aug 24, 2011
23aPS-109 A crystal-field level scheme and magnetic ordering of a heavy electron system PrCu_4Au

Kobayashi H., Saito K., Tomiyasu K., Iwasa K., Zhang S., Ishikawa Y.

Meeting abstracts of the Physical Society of Japan, 66(2) 602-602, Aug 24, 2011
23pGB-3 Study of LaCoO_3 system with lightly doped impurities by inelastic neutron scattering and magnetization measurements

Tomiyasu Keisuke, Kubota Yuuki, Stuhr Uwe, Iwasa Kazuaki, Yamada Kazuyoshi

Meeting abstracts of the Physical Society of Japan, 66(2) 606-606, Aug 24, 2011

Research Projects

Multi-probe study on the spin and orbital quantum critical point in cobaltites

Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Japan Society for the Promotion of Science, Apr, 2018 - Mar, 2022

Tomiyasu Keisuke
Frustration-induced spin textures

Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (S), Japan Society for the Promotion of Science, May, 2017 - Mar, 2022

KAWAMURA Hikaru
Study on novel magnetic order and transport properties in pyrochlore iridium oxides

Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), Japan Society for the Promotion of Science, Apr, 2015 - Mar, 2019

MATSUHIRA KAZUYUKI
Study of spin-lattice dynamics and transports in frustrated spinel oxides

Grants-in-Aid for Scientific Research, Grant-in-Aid for Young Scientists (B), Japan Society for the Promotion of Science, Apr, 2014 - Mar, 2016

Tomiyasu Keisuke
Study on strongly correlated electron systems by using high-order neutron magnetic scattering processes

Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (A), Japan Society for the Promotion of Science, Apr, 2011 - Mar, 2016

Iwasa Kazuaki, ITOH Shinichi, OHOYAMA Kenji, SATOH Taku, TOMIYASU Keisuke, YOKOO Tetsuya, MASUDA Takatsugu, HIRAKA Haruhiro, OKU Takayuki, KIRA Hiroshi, KURAMOTO Yoshio
Neutron scattering spectroscopic study on superconducting-antiferromagnetic phase diagram and pseudo-gap state

Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (A), Japan Society for the Promotion of Science, Apr, 2010 - Mar, 2014

YAMADA Kazuyoshi, FUJITA Masaki, OHOYAMA Kenji, WATANABE Takao, TOMIYASU Keisuke, HIRAKA Haruhiro, MATSUURA Masato, SATO Toyoto, YAMAGUCHI Yasuo, ARAI Masatoshi, SHISHIDO Touetsu
Study of Local Electronic State and the Hybridized Orbital Order under Magnetic Field and Pressure by Resonant Soft X-ray and Neutron Scattering

Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (S), Japan Society for the Promotion of Science, May, 2009 - Mar, 2014

MURAKAMI Youichi, NAKAO Hironori, IWASA Kazuaki, AMEMIYA Kenta, NAKAO Akiko, ISHIHARA Sumio, TOMIYASU Keisuke, KUBOTA Masato, KOIDE Tsuneharu
Inelastic neutron scattering study of spin-charge coupling in spin-frustrated conductors

Grants-in-Aid for Scientific Research, Grant-in-Aid for Young Scientists (B), Japan Society for the Promotion of Science, 2010 - 2012

TOMIYASU Keisuke
幾何学的フラストレート系におけるスピン励起と格子振動の中性子非弾性散乱研究

科学研究費助成事業, 特定領域研究, 日本学術振興会, 2010 - 2011

富安啓輔, 池田伸一, 渡辺忠孝, 原茂生, 高阪勇輔

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