Assigned Class

Faculty of Science

Academic Background

Degree

Doctor of Science , Hokkaido University

Research Career

Research Career

2019 - 2019 , Visiting Scientist, Department of Physics & Astronomy, Iowa State University, US

2018 , Assistant Professor, Graduate School of Science and Engineering, Saitama University

Books, Articles, etc.

Articles

Role of hydrogen bonding in charge-ordered organic conductor α-(BEDT-TTF)2I3 probed by 127I nuclear quadrupole resonance
,Physical Review B,108(11):115108 2023
T. Kobayashi, Y. Kato, H. Taniguchi, T. Tsumuraya, K. Hiraki, and S. Fujiyama

電子ジャーナル

Antiferromagnetic ordering and estimation of the exchange interaction in the π-d system λ-(BEDSe-TTF)2FeCl4 studied using 13CNMR
,Physical Review B,108(15):155112 2023
Rikumaru Saito, Takuya Kobayashi, Hiromi Taniguchi, Shuhei Fukuoka, and Atsushi Kawamoto

電子ジャーナル

Pseudogap formation in organic superconductors
,Physical Review Materials,7(12):124803 2023
Shusaku Imajo, Takuya Kobayashi, Yuki Matsumura, Taiki Maeda, Yasuhiro Nakazawa, Hiromi Taniguchi, and Koichi Kindo

電子ジャーナル

Dynamics of ethylene groups and hyperfine interactions between donor and anion molecules in λ-type organic conductors studied by 69,71Ga-NMR spectroscopy
,Physical Review B,106(24):245103 2022
N. Yasumura, T. Kobayashi, H. Taniguchi, S. Fukuoka, A. Kawamoto
We present the results of ⁶⁹,⁷¹Ga-NMR measurements on an organic antiferromagnet λ-(BEDSe-TTF)₂GaCl₄ [BEDSe-TTF=bis(ethylenediseleno)tetrathiafulvalene], with comparison to reports on λ-(BETS)₂GaCl₄ [BETS=bis(ethylenedithio)tetraselenafulvalene] [T. Kobayashi et al., Phys. Rev.B 102, 235131 (2020)]. We found that the dynamics of two crystallographically independent ethylene groups induce two types of quadrupolar relaxation in the high-temperature region. As the ethylene motion freezes, hyperfine (HF) interactions develop between π spin and Ga nuclear spin below 100 K, and thereby magnetic fluctuations of the π-spin system are detected even from the Ga site. The HF interaction in λ-(BETS)₂GaCl₄ was more than twice as large as in λ-(BEDSe-TTF)₂GaCl₄, implying that the short contacts between Cl atoms and the chalcogens of fulvalene part are essential for the transferred HF interaction. We propose that NMR using nuclei in anion layers is useful for studying interlayer interactions in organic conductors, which have not been studied experimentally. In addition, because the mechanism of the transferred HF interaction is considered to be the same as π–d interaction in isostructural Fe-containing λ-type salts, our findings aid in the understanding of their physical properties.

電子ジャーナル リポジトリ

Magnetic state in the quasi-two-dimensional organic conductor λ−(BEST)2FeCl4 and the path of π−d interaction
,Physical Review B,105(16):165115 2022
Saito, Rikumaru Iida, Youhei Kobayashi, Takuya Taniguchi, Hiromi Matsunaga, Noriaki Fukuoka, Shuhei Kawamoto, Atsushi

Relationship between electronic inhomogeneity and bandwidth in the organic conductor κ−(BEDT−TTF)2Cu[N(CN)2]I studied by 13C NMR spectroscopy
,Physical Review B,105(19):195148 2022
T. Kobayashi, A. Suzuta, A. Kawamoto

Antiferromagnetic ordering of organic Mott insulator λ−(BEDSe-TTF)2GaCl4
,Physical Review B,106(4):045114 2022
A. Ito, T. Kobayashi, D. P. Sari, I. Watanabe, Y. Saito, A. Kawamoto, H. Tsunakawa, K. Satoh, and H. Taniguchi

電子ジャーナル

Enhancement of electron correlations and spin density wave fluctuations of the organic superconductor λ-(BETS)2GaCl4 under pressure proved by 13C NMR
,Physical Review B,103(4):045112 2021
M. Sawada, A. Kawamoto, and T. Kobayashi

Thermodynamic evidence for the formation of a Fulde-Ferrell-Larkin-Ovchinnikov phase in the organic superconductor λ−(BETS)2GaCl4
,Physical Review B,103(22):L220501 2021
S. Imajo, T. Kobayashi, A. Kawamoto, K. Kindo, Y. Nakazawa

Charge imbalance in λ−(BETS)2GaCl4 and their interplay with superconductivity
,Physical Review B,104(4):045108 2021
Olga Iakutkina, Ece Uykur, Takuya Kobayashi, Atsushi Kawamoto, Martin Dressel, Yohei Saito

Spin-density wave in the vicinity of superconducting state in λ−(BETS)2GaBrxCl4−x probed by 13C NMR spectroscopy
,Physical Review Research,2(2):023075 2020
T. Kobayashi, T. Ishikawa, A. Ohnuma, M. Sawada, N. Matsunaga, H. Uehara, and A. Kawamoto

Unconventional superconductivity in λ-(BETS)2GaCl4 probed by C13 NMR
,Physical Review B,102(12):121106(R) 2020
T. Kobayashi, H. Taniguchi, A. Ohnuma, and A. Kawamoto

Spin structure at zero magnetic field and field-induced spin reorientation transitions in a layered organic canted antiferromagnet bordering a superconducting phase
,Physical Review B,102(3):035102 2020
K. Oinuma, N. Okano, H. Tsunakawa, S. Michimura, T. Kobayashi, H. Taniguchi, K. Satoh, J. Angel, I. Watanabe, Y. Ishii, H. Okamoto, and T. Itou

Charge disproportionation in the spin-liquid candidate κ−(ET)2Cu2(CN)3 at 6K revealed by 63Cu NQR measurements
,Physical Review Research,2(4):042023(R) 2020
T. Kobayashi, Q.-P. Ding, H. Taniguchi, K. Satoh, A. Kawamoto, and Y. Furukawa

Selective observation of spin and charge dynamics in an organic superconductor λ−(BETS)2GaCl4 using Ga69,71 NMR measurements
,Physical Review B,102(23):235131 2020
T. Kobayashi, K. Tsuji, A. Ohnuma, and A. Kawamoto

Interacting electron spins in κ−(BEDT-TTF)2Cu[N(CN)2]I investigated by ESR spectroscopy
,Physical Review B,102(21):214430 2020
L. N. Majer, B. Miksch, O. Iakutkina, T. Kobayashi, A. Kawamoto, and M. Dressel

Inhomogeneous electronic state of organic conductor κ−(BEDT-TTF)2Cu[N(CN)2]I studied by C13 NMR spectroscopy
,Physical Review B,100(19):195115 2019
T. Kobayashi, A. Suzuta, K. Tsuji, Y. Ihara, and A. Kawamoto

Gap Symmetry of the Organic Superconductor λ-(BETS)2GaCl4 Determined by Magnetic-Field-Angle-Resolved Heat Capacity
,Journal of the Physical Society of Japan,88(2):023702 2019
S. Imajo, S. Yamashita, H. Akutsu, H. Kumagai, T. Kobayashi, A. Kawamoto, and Y. Nakazawa

Antiferromagnetic Ordering in Organic Conductor λ-(BEDT-TTF)2GaCl4 Probed by 13 C NMR
,Journal of the Physical Society of Japan,87(1):013707 2018
Y. Saito, S. Fukuoka, T. Kobayashi, A. Kawamoto, and H. Mori

Evidence of antiferromagnetic fluctuation in the unconventional superconductor λ-(BETS)2GaCl4 by 13C NMR
,Physical Review B,96(12):125115 2017
T. Kobayashi and A. Kawamoto

電子ジャーナル Web Of Science

Modification of local electronic state by BEDT-STF doping to κ-(BEDT-TTF)2Cu[N(CN)2]Br salt studied by 13C NMR spectroscopy
,Physical Review B,93(9):094515 2016
T. Kobayashi, Y. Ihara, and A. Kawamoto

Thermodynamic Evidence of d-Wave Superconductivity of the Organic Superconductor λ-(BETS)2GaCl4
,Journal of the Physical Society of Japan,85(4):043705 2016
S. Imajo, N. Kanda, S. Yamashita, H. Akutsu, Y. Nakazawa, H. Kumagai, T. Kobayashi, and A. Kawamoto

Microscopic observation of superconducting fluctuations in κ-(BEDT-TTF)2Cu[N(CN)2]Br by 13C NMR spectroscopy
,Physical Review B,89(16):165141 2014
T. Kobayashi, Y. Saito, Y. Ihara, and A. Kawamoto

Presentation

Antiferromagnetic Ordering and Pressure-Induced Anomalous Electronic Phases in λ-(BEDSe-TTF)2GaCl4 Revealed by μSR and NMR
The 6th International Conference on Functional Materials Science 202211
Takuya Kobayashi, Noeru Yasumura, Arisa Ito, Dita Puspita Sari, Isao Watanabe, Shuhei Fukuoka, Atsushi Kawamoto, Hiromi Taniguchi

Pressure-induced superconductivity with transition temperature exceeding 10 K in new organic conductor β'-(BEST)2CuCl2
The 14th International Symposium on Crystalline Organic Metals, Superconductors and Magnets (ISCOM2022) 202209
Takuya Kobayashi, Yoshiya Sugawara, Tomoyuki Tenkawa, Hiromi Taniguchi, Shusaku Imajo, Jun Gochi, and Yoshiya Uwatoko

Pressure-induced anomalous electronic phases of λ-(BEDSe-TTF)2GaCl4 probed by 69,71Ga NMR
The 14th International Symposium on Crystalline Organic Metals, Superconductors and Magnets (ISCOM2022) 202209
Noeru Yasumura, Takuya Kobayashi, Hiromi Taniguchi, Shuhei Fukuoka, Atsushi Kawamoto

Pressure-induced anomalous electronic phases of λ-(BEDSe-TTF)2GaCl4 probed by 69,71Ga NMR
The 14th International Symposium on Crystalline Organic Metals, Superconductors and Magnets (ISCOM2022) 202209
Noeru Yasumura, Takuya Kobayashi, Hiromi Taniguchi, Shuhei Fukuoka, Atsushi Kawamoto

Pressure-induced superconductivity with transition temperature exceeding 10 K in new organic conductor β'-(BEST)2CuCl2
The 14th International Symposium on Crystalline Organic Metals, Superconductors and Magnets (ISCOM2022) 202209
Takuya Kobayashi, Yoshiya Sugawara, Tomoyuki Tenkawa, Hiromi Taniguchi, Shusaku Imajo, Jun Gochi, and Yoshiya Uwatoko

Superconducting State at the Insulating Layer of Organic Superconductor κ-(ET)2Cu[N(CN)2]Br Studied by 63Cu NQR
International Symposium on Crystalline Organic Metals, Superconductors and Magnets 2019 (ISCOM2019) 201909
H. Ozawa, T. Kobayashi, K. Oinuma, H. Tsunakawa, H. Taniguchi, A. Kawamoto

Spin-Density-Wave Near Superconductivity in a System of λ-(BETS)2GaBrxCl4-x Probed by 13C-NMR
International Symposium on Crystalline Organic Metals, Superconductors and Magnets 2019 (ISCOM2019) 201909
T. Ishikawa, A. Kawamoto, T. Kobayashi

Evidence of the Spin-Density-Wave Fluctuation in λ-(BETS)2GaCl4 Probed by 13C and 69/71Ga NMR Spectroscopy
International Symposium on Crystalline Organic Metals, Superconductors and Magnets 2019 (ISCOM2019) 201909
T. Kobayashi, K. Tsuji, T. Ishikawa, A. Ohnuma, and A. Kawamoto

Spin Structure at the Zero Magnetic Field and Field-Induced Spin Reorientations in Deuterated κ-(ET)2Cu[N(CN)2]Br
International Symposium on Crystalline Organic Metals, Superconductors and Magnets 2019 (ISCOM2019) 201909
K. Oinuma, N. Okano, H. Tsunakawa, S. Michimura, T. Kobayashi, H. Taniguchi, K. Satoh, Y. Ishii, Hi. Okamoto, T. Itou

Optical Properties in the Organic Superconductor λ-(BETS)2GaCl4
International Symposium on Crystalline Organic Metals, Superconductors and Magnets 2019 (ISCOM2019) 201909
O. Iakutkina, Y. Saito, T. Kobayashi, A. Kawamoto, M. Dressel

Pressure effect on the inhomogeneous electronic state of organic superconductor k-(BEDT-TTF)2Cu[N(CN)2]I studied by 13C NMR
International Conference on Functional Materials Science 2018 (ICFMS 2018) 201811
Takuya Kobayashi, Akio Suzuta, Kohei Tsuji, Yoshihiko Ihara and Atsushi Kawamoto

13C-NMR Study of Organic Conductor k-(BEDT-TTF)2Cu[N(CN)2]I Under Pressure
International Conference on Science and Technology of Synthetic Metals 2018 (ICSM 2018) 201807
Takuya Kobayashi, Akio Suzuta, Yoshihiko Ihara, and Atsushi Kawamoto

Themes for Joint Research

Organic conductor, Superconductor, Nuclear magnetic resonance, Nuclear quadrupole resonance , Condensed matter physics

Research Grants