| Project/Area Number |
17540332
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Condensed matter physics II
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| Research Institution | Tokyo Metropolitan University |
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Principal Investigator |
SAKAMOTO Hirokazu Tokyo Metropolitan University, Department of Physics, Assistant Professor, 大学院理工学研究科, 助手 (90187047)
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| Co-Investigator(Kenkyū-buntansha) |
MIZOGUCHI Kenji Tokyo Metropolitan University, Department of Physics, Professor, 大学院理工学研究科, 教授 (40087101)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2005: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Keywords | ESR / mixed-stacked / charge-transfer / neutral-ionic transition / pressure / 電荷移動型錯体 / アクセプター / ドナー / モット絶縁体 / 交互積層型電荷移動錯体 / 圧力下ESR |
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| Research Abstract |
Mixed-stacked charge-transfer salts, composed of alternatively aligned donor and acceptor molecules, have neutral and ionic phases. In recently synthesized (BEDT-TTF)(ClMeTCNQ) and (BEDO-TTF)(C_12TCNQ), spin-Peierls transition is suppressed due to BEDT-TTF and BEDO-TTF molecules with strong 2-dimensional interaction. In the analysis of the neutral-ionic transition of (BEDT-TTF)(C1MeTCNQ), we had assumed that the transition temperature is independent of pressure. This leads to the saturation of the spin susceptibility above 1 GPa, which was actually observed. To confirm this assumption, we measured the pressure dependence of the susceptibility up to 2.5 GPa and was able to observed the expected saturation. In (BEDO-TTF)(Cl_2TCNQ), the temperature dependences of the spin susceptibility under several pressures were observed. We obtained the pressure-temperature phase diagram from those results, together with Q-and W-band ESR spectra. It was suggested that the spin system of (BEDO-TTF)(Cl_2TCNQ) is 3-dimensional spin gas under 8 GPa and 3-dimensional spin liquid above 10 GPa. An organic charge-transfer compound, β'-(BEDT-TTF)_2ICl_2, is a Mott insulator, undergoing an antiferromagnetic transition at T_N=22 K under ambient pressure and superconducting transition under the pressure higher than 8 GPa at 14.2 K. The temperature dependences of paramagnetic spin susceptibility have been measured by ESR below 3 GPa to study the electronic states in the region from the insulating to the metallic state. We are preparing a new system for ESR under pressure with a cubic anvil cell, which enables us to measure ESR up to 10 GPa. This system will be used to study the electronic states in the region from the antiferromagnetic to the metallic states of β-(BEDT-TTF)_2ICl_2.
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