Takuya Kobayashi
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
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Takuya Kobayashi has a total of 101 co-authors. Here are the top co-authors by number of shared publications:
- Atsushi Kawamoto
Hokkaido University
15 shared publications - Hiromi Taniguchi
Saitama University
13 shared publications A. Kawamoto
Hokkaido University
9 shared publicationsH. Taniguchi
Saitama University
6 shared publicationsHiromi Taniguchi
Saitama University
5 shared publicationsShinji Michimura
Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
5 shared publications
Latest Publications
- 19 October 2026
- Published by American Physical Society (APS) in Physical Review B
- Vol. 114 (23) , 235122
Investigation of the role of π − d interactions in λ -type salts using pressure-temperature phase diagram
We performed electrical resistivity and $^{13}\mathrm{C}$ nuclear magnetic resonance (NMR) measurements on $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BEDSe}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{FeCl}}_{4}$ under various pressures to obtain insights into the effect of $\ensuremath{\pi}\text{\ensuremath{-}}d$ interactions on the antiferromagnetic (AF) phase. The resistivity shows that the insulating state is maintained up to 2.0 GPa. $^{13}\mathrm{C}$ NMR measurements reveal that the AF transition occurs at 28, 31, and 23 K under 0.5, 1.0, and 2.0 GPa, respectively, indicating that a single AF phase in $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BEDSe}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{FeCl}}_{4}$ is observed under various pressures, whereas two AF phases were observed in $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BEDSe}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{GaCl}}_{4}$. The difference in phase diagrams between the magnetic anion salt, $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BEDSe}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{FeCl}}_{4}$, and the nonmagnetic anion salt, $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BEDSe}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{GaCl}}_{4}$, is attributed to $\ensuremath{\pi}\text{\ensuremath{-}}d$ interactions. These results provide insight into a possible microscopic role of $\ensuremath{\pi}\text{\ensuremath{-}}d$ interactions in the Fe salt. The magnetic properties of $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BEDSe}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{FeCl}}_{4}$ are described by the isolated cluster comprising two dimers and two anions with positive and negative $\ensuremath{\pi}\text{\ensuremath{-}}d$ interactions, suggesting antiferromagnetic coupling between two dimers in the cluster. We also discuss the possible AF structures of $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BEDSe}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{FeCl}}_{4}$.- 19 October 2026
- Published by American Physical Society (APS) in Physical Review B
- Vol. 114 (23) , 235122
Investigation of the role of π − d interactions in λ -type salts using pressure-temperature phase diagram
We performed electrical resistivity and $^{13}\mathrm{C}$ nuclear magnetic resonance (NMR) measurements on $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BEDSe}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{FeCl}}_{4}$ under various pressures to obtain insights into the effect of $\ensuremath{\pi}\text{\ensuremath{-}}d$ interactions on the antiferromagnetic (AF) phase. The resistivity shows that the insulating state is maintained up to 2.0 GPa. $^{13}\mathrm{C}$ NMR measurements reveal that the AF transition occurs at 28, 31, and 23 K under 0.5, 1.0, and 2.0 GPa, respectively, indicating that a single AF phase in $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BEDSe}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{FeCl}}_{4}$ is observed under various pressures, whereas two AF phases were observed in $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BEDSe}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{GaCl}}_{4}$. The difference in phase diagrams between the magnetic anion salt, $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BEDSe}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{FeCl}}_{4}$, and the nonmagnetic anion salt, $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BEDSe}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{GaCl}}_{4}$, is attributed to $\ensuremath{\pi}\text{\ensuremath{-}}d$ interactions. These results provide insight into a possible microscopic role of $\ensuremath{\pi}\text{\ensuremath{-}}d$ interactions in the Fe salt. The magnetic properties of $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BEDSe}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{FeCl}}_{4}$ are described by the isolated cluster comprising two dimers and two anions with positive and negative $\ensuremath{\pi}\text{\ensuremath{-}}d$ interactions, suggesting antiferromagnetic coupling between two dimers in the cluster. We also discuss the possible AF structures of $\ensuremath{\lambda}\text{\ensuremath{-}}{(\mathrm{BEDSe}\text{\ensuremath{-}}\mathrm{TTF})}_{2}{\mathrm{FeCl}}_{4}$.- Open Access
- 15 April 2026
- Published by Physical Society of Japan in Journal of the Physical Society of Japan
- Vol. 95 (4)
Ambient-Pressure Organic Dirac Electron State in α -(BETS) 2 AuCl 2
We report an ambient-pressure Dirac electron (DE) state in a new organic conductor, α-(BETS)2AuCl2 [BETS = bis(ethylenedithio)tetraselenafulvalene]. This salt exhibits characteristic transport prop...
- 15 April 2026
- Published by Physical Society of Japan in Journal of the Physical Society of Japan
- Vol. 95 (4)
Open AccessAmbient-Pressure Organic Dirac Electron State in α -(BETS) 2 AuCl 2
We report an ambient-pressure Dirac electron (DE) state in a new organic conductor, α-(BETS)2AuCl2 [BETS = bis(ethylenedithio)tetraselenafulvalene]. This salt exhibits characteristic transport prop...
- 9 April 2026
- Published by Royal Society of Chemistry (RSC) in Journal of Materials Chemistry C
- Vol. 14 (20) , 8824-8830
A low-dimensional quantum spin system separated by charge-disproportionated nonmagnetic BEST layers in (BEST) 3 Zn(NCS) 4
We report the structural and physical properties of a novel low-dimensional organic antiferromagnet, (BEST) 3 Zn(NCS) 4 , where BEST denotes bis(ethylenediseleno)tetrathiafulvalene.
- 9 April 2026
- Published by Royal Society of Chemistry (RSC) in Journal of Materials Chemistry C
- Vol. 14 (20) , 8824-8830
A low-dimensional quantum spin system separated by charge-disproportionated nonmagnetic BEST layers in (BEST) 3 Zn(NCS) 4
We report the structural and physical properties of a novel low-dimensional organic antiferromagnet, (BEST) 3 Zn(NCS) 4 , where BEST denotes bis(ethylenediseleno)tetrathiafulvalene.
- 4 February 2026
- Published by American Physical Society (APS) in Physical Review B
- Vol. 113 (6)
Determination of charge ordering pattern of the organic salt α ′ − ( ET ) 2 IBr 2 using x-ray diffraction
- 4 February 2026
- Published by American Physical Society (APS) in Physical Review B
- Vol. 113 (6)
Determination of charge ordering pattern of the organic salt α ′ − ( ET ) 2 IBr 2 using x-ray diffraction
- 2 January 2026
- Published by Taylor & Francis in High Pressure Research
- Vol. 46 (1) , 37-46
Pressure-induced Mott transition and signatures of superconductivity in β ′-(BEDT-TTF) 2 R CF 2 SO 3 ( R = CF 3 , SF 5 )
- 2 January 2026
- Published by Taylor & Francis in High Pressure Research
- Vol. 46 (1) , 37-46
Pressure-induced Mott transition and signatures of superconductivity in β ′-(BEDT-TTF) 2 R CF 2 SO 3 ( R = CF 3 , SF 5 )
- 25 September 2025
- Published by American Physical Society (APS) in Physical Review B
- Vol. 112 (10)
Pressure-induced nearly perfect rectangular lattice and superconductivity in the organic molecular crystal- 25 September 2025
- Published by American Physical Society (APS) in Physical Review B
- Vol. 112 (10)
Pressure-induced nearly perfect rectangular lattice and superconductivity in the organic molecular crystal- 10 September 2025
- Published by American Chemical Society (ACS) in Inorganic Chemistry
- Vol. 64 (37) , 18751-18760
Charge-Transfer Complex κ-(BEST)2Cu2(CN)3 Analogous to Organic Spin Liquid Candidate
We report the structural, electrical, and magnetic properties of the organic conductor κ-(BEST)2Cu2(CN)3 (BEST: bis(ethylenediseleno)-tetrathiafulvalene; abbreviated as κ-BEST-CN), which is isostructural with the quantum spin liquid candidate κ-(ET)2Cu2(CN)3 (ET: bis(ethylenedithio)tetrathiafulvalene; abbreviated as κ-ET-CN). Resistivity measurements demonstrate that κ-BEST-CN exhibits semiconducting behavior, governed by the same conducting mechanism as κ-ET-CN. Under a pressure of ∼0.1 GPa, κ-BEST-CN undergoes a superconducting transition with an onset temperature of ∼4 K. From the comparison of the critical pressures of superconductivity between κ-ET-CN and κ-BEST-CN, κ-BEST-CN can be regarded as a chemically pressurized analogue of κ-ET-CN. Therefore, κ-BEST-CN, in which only the effective pressure changes without altering the anion structure, is considered a valuable reference material for elucidating the enigmatic properties observed in κ-ET-CN. Furthermore, the spin susceptibility of κ-BEST-CN is slightly larger than that of κ-ET-CN and shows weaker temperature dependence, which cannot be explained by the localized spin model. This behavior clarifies the anomalous magnetic properties of a system with frustration near the Mott transition, serving to stimulate future theoretical research.
- 10 September 2025
- Published by American Chemical Society (ACS) in Inorganic Chemistry
- Vol. 64 (37) , 18751-18760
Charge-Transfer Complex κ-(BEST)2Cu2(CN)3 Analogous to Organic Spin Liquid Candidate
We report the structural, electrical, and magnetic properties of the organic conductor κ-(BEST)2Cu2(CN)3 (BEST: bis(ethylenediseleno)-tetrathiafulvalene; abbreviated as κ-BEST-CN), which is isostructural with the quantum spin liquid candidate κ-(ET)2Cu2(CN)3 (ET: bis(ethylenedithio)tetrathiafulvalene; abbreviated as κ-ET-CN). Resistivity measurements demonstrate that κ-BEST-CN exhibits semiconducting behavior, governed by the same conducting mechanism as κ-ET-CN. Under a pressure of ∼0.1 GPa, κ-BEST-CN undergoes a superconducting transition with an onset temperature of ∼4 K. From the comparison of the critical pressures of superconductivity between κ-ET-CN and κ-BEST-CN, κ-BEST-CN can be regarded as a chemically pressurized analogue of κ-ET-CN. Therefore, κ-BEST-CN, in which only the effective pressure changes without altering the anion structure, is considered a valuable reference material for elucidating the enigmatic properties observed in κ-ET-CN. Furthermore, the spin susceptibility of κ-BEST-CN is slightly larger than that of κ-ET-CN and shows weaker temperature dependence, which cannot be explained by the localized spin model. This behavior clarifies the anomalous magnetic properties of a system with frustration near the Mott transition, serving to stimulate future theoretical research.
- 15 August 2025
- Published by Physical Society of Japan in Journal of the Physical Society of Japan
- Vol. 94 (8)
Metastable Phase with Enhanced Spin Susceptibility Located between Charge Glass Phase and Charge Order Phase in a Layered Organic Conductor
Geometrical charge frustration is believed to induce a charge glass state in the layered organic conductor θ-(BEDT-TTF) 2 RbZn(SCN) 4 when rapidly cooled at rates exceeding 5 K/min during a charge order transition at around 200 K [BEDT-TTF: bis(ethylenedithio)tetrathiafulvalene]. Furthermore, when the charge glass state is held at constant temperatures, it evolves into a charge-ordered state, which may be considered as the crystallization of the charge. Nucleation of the charge-ordered state is expected to become significant in the low-temperature range below 165 K. However, magnetic susceptibility measurements enable us to claim that a metastable state exists during this crystallization process, which is distinct from both the charge glass and charge-ordered states. This state is thought to correspond to an intermediate state, as suggested by measurements of electrical conductivity and 13 C-NMR. The metastable state exhibits a higher spin susceptibility than the other two states, and since nucleation of it occurs from the charge glass state in which electron transport strongly confined to two-dimensional layers, we propose that it may correspond to a purely two-dimensional charge-ordered phase. Our results are expected to provide insight into a key aspect of the rich electronic phases inherent in charge-frustrated materials.
- 15 August 2025
- Published by Physical Society of Japan in Journal of the Physical Society of Japan
- Vol. 94 (8)
Metastable Phase with Enhanced Spin Susceptibility Located between Charge Glass Phase and Charge Order Phase in a Layered Organic Conductor
Geometrical charge frustration is believed to induce a charge glass state in the layered organic conductor θ-(BEDT-TTF) 2 RbZn(SCN) 4 when rapidly cooled at rates exceeding 5 K/min during a charge order transition at around 200 K [BEDT-TTF: bis(ethylenedithio)tetrathiafulvalene]. Furthermore, when the charge glass state is held at constant temperatures, it evolves into a charge-ordered state, which may be considered as the crystallization of the charge. Nucleation of the charge-ordered state is expected to become significant in the low-temperature range below 165 K. However, magnetic susceptibility measurements enable us to claim that a metastable state exists during this crystallization process, which is distinct from both the charge glass and charge-ordered states. This state is thought to correspond to an intermediate state, as suggested by measurements of electrical conductivity and 13 C-NMR. The metastable state exhibits a higher spin susceptibility than the other two states, and since nucleation of it occurs from the charge glass state in which electron transport strongly confined to two-dimensional layers, we propose that it may correspond to a purely two-dimensional charge-ordered phase. Our results are expected to provide insight into a key aspect of the rich electronic phases inherent in charge-frustrated materials.
- Open AccessCharge-Transfer Complex $κ$-(BEST)$_2$Cu$_2$(CN)$_3$ Analogous to Organic Spin Liquid CandidateWe report the structural, electrical, and magnetic properties of the organic conductor $κ$-(BEST)$_2$Cu$_2$(CN)$_3$ (BEST: bis(ethylenediseleno)tetrathiafulvalene; abbreviated as $κ$-BEST-CN), which is isostructural with the quantum spin liquid candidate $κ$-(ET)$_2$Cu$_2$(CN)$_3$ (ET: bis(ethylenedithio)tetrathiafulvalene; abbreviated as $κ$-ET-CN). Resistivity measurements demonstrate that $κ$-BEST-CN exhibits semiconducting behavior, governed by the same conducting mechanism as $κ$-ET-CN. Under a pressure of ~0.1 GPa, $κ$-BEST-CN undergoes a superconducting transition with an onset temperature of ~4 K. From the comparison of the critical pressures of superconductivity between $κ$-ET-CN and $κ$-BEST-CN, $κ$-BEST-CN can be regarded as a chemically pressurized analogue of $κ$-ET-CN. Therefore, $κ$-BEST-CN, in which only the effective pressure changes without altering the anion structure, is considered a valuable reference material for elucidating the enigmatic properties observed in $κ$-ET-CN. Furthermore, the spin susceptibility of $κ$-BEST-CN is slightly larger than that of $κ$-ET-CN and shows weaker temperature dependence, which cannot be explained by the localized spin model. This behavior clarifies the anomalous magnetic properties of a system with frustration near the Mott transition, serving to stimulate future theoretical research.Open AccessCharge-Transfer Complex $κ$-(BEST)$_2$Cu$_2$(CN)$_3$ Analogous to Organic Spin Liquid CandidateWe report the structural, electrical, and magnetic properties of the organic conductor $κ$-(BEST)$_2$Cu$_2$(CN)$_3$ (BEST: bis(ethylenediseleno)tetrathiafulvalene; abbreviated as $κ$-BEST-CN), which is isostructural with the quantum spin liquid candidate $κ$-(ET)$_2$Cu$_2$(CN)$_3$ (ET: bis(ethylenedithio)tetrathiafulvalene; abbreviated as $κ$-ET-CN). Resistivity measurements demonstrate that $κ$-BEST-CN exhibits semiconducting behavior, governed by the same conducting mechanism as $κ$-ET-CN. Under a pressure of ~0.1 GPa, $κ$-BEST-CN undergoes a superconducting transition with an onset temperature of ~4 K. From the comparison of the critical pressures of superconductivity between $κ$-ET-CN and $κ$-BEST-CN, $κ$-BEST-CN can be regarded as a chemically pressurized analogue of $κ$-ET-CN. Therefore, $κ$-BEST-CN, in which only the effective pressure changes without altering the anion structure, is considered a valuable reference material for elucidating the enigmatic properties observed in $κ$-ET-CN. Furthermore, the spin susceptibility of $κ$-BEST-CN is slightly larger than that of $κ$-ET-CN and shows weaker temperature dependence, which cannot be explained by the localized spin model. This behavior clarifies the anomalous magnetic properties of a system with frustration near the Mott transition, serving to stimulate future theoretical research.