Publications
2025
- Broken Time-Reversal Symmetry Detected by Tunneling Spectroscopy of Superconducting Pd-doped CaAgP,
Naoki Matsubara, Rikizo Yano, Kazushige Saigusa, Koshi Takenaka, Yoshihiko Okamoto, Yukio Tanaka, Satoshi Kashiwaya,
submitted. (arXiv:2412.08335) - Observation of Current-induced Lattice Distortion in Spin-orbit Coupled Iridium Oxide Ca5Ir3O12,
Keisuke Kadohiro, Hiroki Hanate, Momoka Hayashida, Takumi Hasegawa, Hironori Nakao, Yoshihiko Okamoto, Koji Miyazaki, Satoshi Tsutsui, Kazuyuki Matsuhira*,
J. Phys. Soc. Jpn., accepted. - Topological Semimetal KAlGe with Novel Electronic Instability,
Toshiya Ikenobe*, Takahiro Yamada, Jun-ichi Yamaura, Tamio Oguchi, Ryutaro Okuma, Daigorou Hirai, Hajime Sagayama, Yoshihiko Okamoto, and Zenji Hiroi,
Chem. Mater., accepted. - Superconductivity in Hexagonal Zr6CoAl2-Type Zr6RuBi2 and Zr6FeBi2,
Kosuke Yuchi*, Daisuke Nishio-Hamane, Keita Kojima, Kodai Moriyama, Ryutaro Okuma, and Yoshihiko Okamoto*,
J. Phys. Soc. Jpn. 94, 013701(1-5) (2025). (arXiv:2410.16684)
2024
- Compass-Model Physics on the Hyperhoneycomb Lattice in the Extreme Spin-Orbit Regime,
Ryutaro Okuma*, Kylie MacFarquharson, Roger D. Johnson, David Voneshen, Pascal Manuel, and Radu Coldea,
Nat. Commun. 15, 10615(1-8) (2024). (open access)
(Press Release from University of Oxford: Breakthrough discovery in magnetic materials could unlock new quantum states) - Electronic Self-Organization in the β-Pyrochlore Oxide CsW2O6,
Yoshihiko Okamoto*,
J. Phys. Soc. Jpn. 93, 111006(1-16) (2024). (open access) (arXiv:2406.13981) - Selective Synthesis and Crystal Chemistry of Candidate Rare-Earth Kitaev Materials: Honeycomb and Hyperhoneycomb Na2PrO3,
Ryutaro Okuma*, Kylie MacFarquharson, and Radu Coldea,
Inorg. Chem. 63, 15941-15950 (2024). - Unbalanced Charge Distribution Stabilized by Orbital Ordering,
Yoshihiko Okamoto*,
JPSJ News and Comments 21, 13(1-2) (2024). (open access) - Pseudo-One-Dimensional Ribbon Chain Cluster Realized under High Pressure in 1T−VSe2,
T. Hara, N. Katayama*, S. Kitou, K. Kojima, S. Kawaguchi, and H. Sawa,
Phys. Rev. B 110, L020103(1-6) (2024). - Electric Field-Induced Volume Change in Pyro-Vanadate-Phosphates: Toward an Alternative Actuator Architecture,
K. Takada, J. Shibutani, K .Yagi, F. Ikawa, Y. Yokoyama, D. Hirai, Y. Okamoto, N. Katayama, Y. Uemura, L. M. G. H. Chavas, T. Hatano, A. Fujita, and K. Takenaka*,
Appl. Phys. Lett. 125, 041903(1-6) (2024). - Emergent Topological Magnetism in Hund's Excitonic Insulator,
R. Okuma*, K. Yamagami*, Y. Fujisawa, C. H. Hsu, Y. Obata, N. Tomoda, M. Dronova, K. Kuroda, H. Ishikawa, K. Kawaguchi, K. Aido, K. Kindo, Y. H. Chan, H. Lin, Y. Ihara, T. Kondo, Y. Okada,
submitted. (arXiv:2405.16781) - Anisotropic Optical Conductivity Accompanied by a Small Energy Gap in One-Dimensional Thermoelectric Telluride Ta4SiTe4,
Fumiya Matsunaga, Yoshihiko Okamoto*, Yasunori Yokoyama, Kanji Takehana, Yasutaka Imanaka, Yuto Nakamura, Hideo Kishida, Shoya Kawano, Kazuyuki Matsuhira, and Koshi Takenaka,
Phys. Rev. B 109, L161105(1-6) (2024). (arXiv:2311.13031) - Nonmagnetic Ground State in RuO2 Revealed by Muon Spin Rotation,
M. Hiraishi, H. Okabe, A. Koda, R. Kadono, T. Muroi, D. Hirai, and Z. Hiroi,
Phys. Rev. Lett. 132, 166702(1-6) (2024). - Superconductivity in Ternary Zirconium Telluride Zr6MTe2 with 3d Transition Metals,
Haruka Matsumoto, Youichi Yamakawa, Ryutaro Okuma, Daisuke Nishio-Hamane, and Yoshihiko Okamoto*,
J. Phys. Soc. Jpn. 93, 023705(1-5) (2024). (arXiv:2401.04870) - Superconductivity in Ternary Germanide ScPdGe and Silicide ScPdSi,
Yusaku Shinoda, Yoshihiko Okamoto*, Youichi Yamakawa, Hiroshi Takatsu, Hiroshi Kageyama, Daigorou Hirai, and Koshi Takenaka,
J. Phys. Soc. Jpn. 93, 023701(1-4) (2024). (arXiv:2312.06045)
2023
- Electroactive Actuator Composites Using Volume Change Induced by Insulator-to-Metal Transition in VO2,
K. Takenaka*, Y. Mizuno, J. Shibutani, K. Kishida, K. Takada, K. Yagi, Y. Yokoyama, N. Katayama, Y. Okamoto, D. Hirai, T. Hatano, and A. Fujita,
Appl. Phys. Lett. 123, 231905(1-6) (2023).
(Featured Article) - Evidence of Unconventional Superconductivity on the Surface of the Nodal Semimetal CaAg1-xPdxP,
Rikizo Yano*, Shota Nagasaka, Naoki Matsubara, Kazushige Saigusa, Tsuyoshi Tanda, Seiichiro Ito, Ai Yamagake, Yoshihiko Okamoto*, Koshi Takenaka, and Satoshi Kashiwaya*,
Nat. Commun. 14, 6817(1-6) (2023) (open access). - Superconductivity in Ternary Scandium Telluride Sc6MTe2 with 3d, 4d, and 5d Transition Metals,
Yusaku Shinoda, Yoshihiko Okamoto*, Youichi Yamakawa, Haruka Matsumoto, Daigorou Hirai, and Koshi Takenaka,
J. Phys. Soc. Jpn. 92, 103701(1-5) (2023). (arXiv:2304.01444) (oprn access)
(JPSJ Papers of Editors' Choice)
(JPSJ Hot Topics: A New Superconductor Family with Various Magnetic Elements) - Structural and Electronic Properties of a Triangular Lattice Magnet NaPrTe2 Compared with NaNdTe2 and NaTbTe2,
Koki Eto, Yoshihiko Okamoto*, Naoyuki Katayama, Hajime Ishikawa, Koichi Kindo, and Koshi Takenaka,
J. Phys. Soc. Jpn. 92, 094707(1-6) (2023). (arXiv:2307.06516) - Signatures of a Magnetic Superstructure Phase Induced by Ultrahigh Magnetic Fields in a Breathing Pyrochlore Antiferromagnet,
Masaki Gen*, Akihiko Ikeda, Kazushi Aoyama, Harald O. Jeschke, Yuto Ishii, Hajime Ishikawa, Takeshi Yajima, Yoshihiko Okamoto, Xuguang Zhou, Daisuke Nakamura, Shojiro Takeyama, Koichi Kindo, Yasuhiro H. Matsuda, Yoshimitsu Kohama*,
Proc. Natl. Acad. Sci. 120, e2302756120(1-7) (2023). (arXiv:2301.09509) - Large Magnetic-Field-Induced Strains in Sintered Chromium Tellurides,
Yuki Kubota, Yoshihiko Okamoto*, Tomoya Kanematsu, Takeshi Yajima, Daigorou Hirai, and Koshi Takenaka,
Appl. Phys. Lett. 122, 042404(1-6) (2023). (arXiv:2211.13388)
(News: Science Japan "Group led by The Institute for Solid State Physics at The University of Tokyo discovers new material that significantly expands when a magnetic field is applied: Shows promise for new actuators") - Systematic Study on the Role of the Third Zn-Site Element in Zn2-xMgxP2O7 Showing Giant Negative Thermal Expansion,
Ryota Kasugai, Yoshifumi Kadowaki, Yasunori Yokoyama, Naoyuki Katayama, Yoshihiko Okamoto, and Koshi Takenaka*,
Mater. Trans. 64, 638-642 (2023). - Two-Band Model and Point Contact Spectroscopy of Nodal-Line Semimetal CaAg0.9Pd0.1P,
Naoki Matsubara*, Shota Nagasaka, Rikizo Yano, Kazushige Saigusa, Yusaku Shinoda, Yoshihiko Okamoto, Koshi Takenaka, and Satoshi Kashiwaya,
JPS Conf. Proc. 38, 011028(1-6) (2023).
2022
- Electronic Properties of Pyrochlore-Type Ca2Ir2O7,
Yuki Nakayama, Yoshihiko Okamoto*, Daigorou Hirai, and Koshi Takenaka,
J. Phys. Soc. Jpn., 91, 125002(1-2) (2022). (arXiv:2211.09290) - Electronic Structure Reconstruction by Trimer Formation in CsW2O6 Studied by X-Ray Photoelectron Spectroscopy,
R. Nakamura, D. Takegami, A. Melendez-Sans, L. H. Tjeng, M. Okawa, T. Miyashino, N. L. Saini, M. Kitamura, D. Shiga, H. Kumigashira, M. Yoshimura, K.-D. Tsuei, Y. Okamoto, and T. Mizokawa,
Phys. Rev. B, 106, 195104(1-6) (2022). - Electrical-Field-Induced Insulator-to-Metal Transition in Samarium Monosulfides,
K. Kishida, J. Shibutani, T. Hatano, Y. Yokoyama, N. Katayama, Y. Okamoto, Y. Nakamura, H. Kishida, H. S. Suzuki, K. Takehana, Y. Imanaka, and K. Takenaka*,
Appl. Phys. Lett. 121, 121901(1-6) (2022). - Complex Magnetic Phase Diagram with a Small Phase Pocket in a Three-Dimensional Frustrated Magnet CuInCr4S8,
M. Gen*, H. Ishikawa, A. Ikeda, A. Miyake, Z. Yang, Y. Okamoto, M. Mori, K. Takenaka, T. Kurumaji, Y. Tokunaga, T. Arima, M. Tokunaga, K. Kindo, Y. H. Matsuda, Y. Kohama,
Phys. Rev. Research 4, 033148(1-13) (2022). (arXiv:2112.08990)