Thermodynamic Investigation of Electron Correlation Effects in Organic Salts

有机盐中电子相关效应的热力学研究

• 批准号: 11640362
• 负责人: NAKAZAWA Yasuhiro
• 金额: $ 1.98万
• 依托单位: Osaka University (2000-2001)Okazaki National Research Institutes (1999)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640362/
• 关键词: Electron Correlation; Mott Transition; Charge Order; Heat Capacity; 電子相関効果; 低温電子比熱

This project is proposed to establish a systematic understanding of the various type of insulation mechanism due to electron correlation effects, which appears in organic 2 : 1salts consisting of BEDT-TTF and DCNQI molecules. Throughout the project, we tried to see the nature of the ground state and low-energy excitations from it by means of the thermodynamic measurements.In the fiscal year 1999, we focussed on studying the peculiar properties around the Mott boundary in the phase diagram of κ-(BEDT-TTF)_2X system. Using the chemical pressure effect produed by partial deuteration in BEDT-TTF molecules, we have got the information on the variation of γ-term across the Mott boundary for the first time. The γvalue decrease monotonously with approaching the insulating phase and no Brinkmann-Rice type enhancement was observed. The psuedo-gap picture established in high-Tc oxide seems to be favored in this system.Next year, we have dealt with the non-dimeric quasi-one-dimensional system (DI-DCNQI)_2Ag in terms of charge-ordering due to the long-range Coulomb interaction, V. Although we could not find any thermal anomaly around the charge-order transition, the existence of large one-dimensional spin excitations which is sensitively suppressed by external magnetic fields has been observed. The possibility of field induced spin-gap is suggested in this system.

该项目旨在建立对由BEDT-TTF和DCNQI分子组成的有机2：1盐中电子相关效应引起的各种类型绝缘机制的系统理解。在整个项目中，我们试图通过热力学测量来了解基态的性质和低能激发，在1999财政年度，我们重点研究了κ-（BEDT-TTF）_2X体系相图中Mott边界附近的特殊性质。利用BEDT-TTF分子中部分氘化产生的化学压力效应，我们首次得到了γ项在Mott边界附近的变化信息。γ值随着接近绝缘相而单调下降，未观察到Brinkmann-Rice型增强。在高Tc氧化物中建立的赝能隙图象似乎更适合于这个系统。明年，我们将处理非二聚体的准一维系统（DI-DCNQI）_2Ag的电荷有序性，虽然在电荷有序跃迁附近没有发现热异常，已经观察到大的一维自旋激发的存在，其被外部磁场灵敏地抑制。提出了在该系统中存在场致自旋带隙的可能性。

项目成果

Y.Nakazawa: "Thermodynamics of BEDT-TTF based Dimeric Salts,"Synthetic Metals. 103. 1903-1904 (1999)

Y.Nakazawa：“基于 BEDT-TTF 的二聚盐的热力学”，合成金属。

A. Sato et al: "Magnetic Properties of λ-BETS_2(Fe_xGa_(1-x)Cl_4 Exhibiting Superconductor-to-Insulator Transition (BETS=bis(ethlenedithiotetraselenafulvalene ; 0.35<x<0.5)"Phys. Rev.. B61. 111-114 (2000)

A. Sato 等人：“λ-BETS_2(Fe_xGa_(1-x)Cl_4 的磁性表现出超导体到绝缘体的转变 (BETS=bis(ethleneditthiotetraselenafulvalene ; 0.35<x<0.5))”Phys. Rev.. B61. 111 -114 (2000)

A. Sato, E. Ojima, H. Akutsu, Y. Nakazawa, H. Kobayashi, H.Tanaka, A. Kobayashi, P. Cassoux: "Magnetic Properties of λ-(BETS)_2(Fe_XGa_<1-X>)Cl_4 Exhibiting Superconductor-to-Insulator Transition"Physical Review B. 61. 111-114 (2000)

A. Sato、E. Ojima、H. Akutsu、Y. Nakazawa、H. Kobayashi、H.Tanaka、A. Kobayashi、P. Cassoux：“λ-(BETS)_2(Fe_XGa_<1-X>) 的磁性Cl_4 展示超导体到绝缘体的转变”物理评论 B. 61. 111-114 (2000)

Y.Nakazawa: "Electronic Specific Heat at the Boundary Region of Mott Trunsition in Two-Dimensional Electronic System of к-(BEDT-TTF)_2Cu[N(CN)_2]Br"Physical Review B. 61. R16295-R16298 (2000)

Y.Nakazawa：“к-(BEDT-TTF)_2Cu[N(CN)_2]Br二维电子系统中莫特传输边界区域的电子比热”物理评论 B.61.R16295-R16298 (2000 ）

Y. Nakazawa et al: "Electronic Specific Heat at the Boundary region of Mott Transition in Two-Dimensional Electronic System of κ-(BEDT-TTF)_2Cu[N(CN)_2]Br"Phys. Rev.. B61. R16295-16298 (2000)

Y. Nakazawa 等人：“κ-(BEDT-TTF)_2Cu[N(CN)_2]Br 二维电子系统中莫特跃迁边界区域的电子比热”Phys Rev. B61-。 16298 (2000)