C-13 NMR study on the charge-disproportionated conducting state in the quasi-two-dimensional organic conductor alpha-(BEDT-TTF)(2)I-3

Article

关键词: BEDT-TTF;    THERMAL-CONDUCTIVITY;    BETA-PHASES;    AB-PLANE;    BETA-(BEDT-TTF)2I3;    RELAXATION;    TRANSPORT;    INSULATOR;    METALS;   

DOI  :  10.1103/PhysRevB.84.125133

来源: SCIE

【 摘 要 】

The conducting state of the quasi-two-dimensional organic conductor alpha-(BEDT-TTF)(2)I-3 at ambient pressure is investigated with C-13 NMR measurements, which separate the local electronic states at three nonequivalent molecular sites (A, B, and C). The spin susceptibility and electron correlation effect are revealed in a locally resolved manner. While there is no remarkable site dependence around room temperature, the local spin susceptibility gradually disproportionates among the nonequivalent sites with decreasing temperature. The disproportionation ratio yields 5:4:6 for A:B:C molecules at 140 K. Distinct site and temperature dependences are also observed in the Korringa ratio K-i alpha (1/T1T)(i)K-i(-2) (i = A, B, and C), which is a measure of the strength and the type of electron correlations. The values of K-i point to sizable antiferromagnetic spin correlation. We argue the present results in terms of the theoretical prediction of the peculiar site-specific reciprocal-space (k-space) anisotropy on the tilted Dirac cone, and discuss the k-dependent profiles of the spin susceptibility and electron correlation on the cone.

【 授权许可】

Free