Koichi Kindo
University of Tokyo
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Publication
Featured researches published by Koichi Kindo.
Journal of the Physical Society of Japan | 2000
Kenzo Onizuka; Hiroshi Kageyama; Yasuo Narumi; Koichi Kindo; Yutaka Ueda; Tsuneaki Goto
High-field magnetization measurements up to 57 T have been performed at 0.08 K in a single crystal of a two-dimensional spin-gap material SrCu 2 (BO 3 ) 2 . We successfully observed the predicted plateau at 1/3 of the total magnetization around 50 T, in which the magnetic superstructure is characterized by a novel stripe order of triplets. The 1/3 plateau is much wider than the previously observed 1/4 and 1/8 plateaux.
Journal of the Physical Society of Japan | 2001
Tetsuya Takeuchi; Tetsutaro Inoue; Kiyohiro Sugiyama; Dai Aoki; Yoshihumi Tokiwa; Yoshinori Haga; Koichi Kindo; Yoshichika Onuki
We studied the magnetic properties in a non-magnetic heavy-fermion compound CeIrIn 5 and an antiferromagnetic compound CeRhIn 5 with the tetragonal structure. High-field magnetization of CeIrIn 5 s...
Journal of the Physical Society of Japan | 1990
Kiyohiro Sugiyama; Hiroyuki Fuke; Koichi Kindo; Kenji Shimohata; A.A. Menovsky; J. A. Mydosh; Muneyuki Date
High-field magnetization and magnetoresistance of URu 2 Si 2 single crystal are investigated up to 600 kOe. Three-step metamagnetic transitions are obtained with the transition fields of 358, 365 and 396 kOe at 1.3 K. The experimental results are explained quantitatively by introducing the model that the heavy Fermion state produced by the mixing of the f- and conduction electrons is destroyed by applying the field and that the exchange interactions between the recovered local f-electron magnetic moments on the uranium atom play an important role on the magnetic properties at high field. The frustration due to the exchange interactions induces the three-step metamagnetic transitions.
Journal of the Physical Society of Japan | 2009
Hiroyuki Yoshida; Yoshihiko Okamoto; Takashi Tayama; Toshiro Sakakibara; Masashi Tokunaga; Akira Matsuo; Yasuo Narumi; Koichi Kindo; Makoto Yoshida; Masashi Takigawa; Zenji Hiroi
Magnetic properties of the spin-1/2 kagome-like compound volborthite are studied using a high-quality polycrystalline sample. It is evidenced from magnetization and specific heat measurements that the spins on the kagome lattice still fluctuate at low temperature, down to T =60 mK that corresponds to 1/1500 of the nearest-neighbor antiferromagnetic interaction, exhibiting neither a conventional long-range order nor a spin gap. In contrast, 51 V NMR experiments revealed a sharp peak at 1 K in relaxation rate, which indicates that a certain exotic order occurs. Surprisingly, we have observed three “steps” in magnetization as a function of magnetic field, suggesting that at least four liquid-like or other quantum states exist under magnetic fields.
Journal of the Physical Society of Japan | 2009
Takanori Kida; Takahiro Matsunaga; Masayuki Hagiwara; Yoshikazu Mizuguchi; Yoshihiko Takano; Koichi Kindo
We have performed electrical resistivity measurements of a polycrystalline sample of FeSe 0.25 Te 0.75 , which exhibits superconductivity at T c ∼14 K, in magnetic fields up to 55 T to determine the upper critical field µ 0 H c2 . In this compound, very large slopes of µ 0 H c2 at the onset, the mid-point, the zero-resistivity temperatures on superconductivity are determined to be -13.7, -10.1, and -6.9 T/K, respectively. The observed µ 0 H c2 ( T )s of this compound are considerably smaller than those expected from the Werthamer–Helfand–Hohenberg model, manifesting the Pauli limiting behavior. These results suggest that this compound shows the spin-singlet pairing in the superconducting state.
Physical Review B | 2015
Yumi Kubota; Hidekazu Tanaka; Toshio Ono; Yasuo Narumi; Koichi Kindo
The layered compound
Physical Review B | 2003
Hiroya Sakurai; Kazunori Takada; Shunsuke Yoshii; Takayoshi Sasaki; Koichi Kindo; Eiji Takayama-Muromachi
\alpha
Journal of the Physical Society of Japan | 2007
Yusuke Okuda; Yuichiro Miyauchi; Yuki Ida; Yuuji Takeda; Chie Tonohiro; Yasuhiro Oduchi; T. Yamada; Nguyen Duc Dung; Tatsuma D. Matsuda; Yoshinori Haga; Tetsuya Takeuchi; Masayuki Hagiwara; Koichi Kindo; Hisatomo Harima; Kiyohiro Sugiyama; Rikio Settai; Y. Ōnuki
-RuCl
Journal of the Physical Society of Japan | 2001
Naoyuki Tateiwa; Katsumi Hanazono; Tatsuo C. Kobayashi; Kiichi Amaya; Tetsutaro Inoue; Koichi Kindo; Yoshihiro Koike; N. Metoki; Yoshinori Haga; Rikio Settai; Y. Ōnuki
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Journal of the Physical Society of Japan | 1996
Tadashi Fukuhara; Kunihiko Maezawa; Hitoshi Ohkuni; Junji Sakurai; Hideyuki Sato; Hisashi Azuma; Kiyohiro Sugiyama; Yoshichika Onuki; Koichi Kindo
is composed of a honeycomb lattice of magnetic Ru