Theory of the Hall coefficient and resistivity for the layered organic superconductors kappa-(BEDT-TTF)(2)X - art. no. 134524

In the organic superconducting kappa-(BEDT-TTF)(2)X compounds, various tran sport phenomena exhibit striking non-Fermi liquid behaviors, which should b e the important clues to understanding the electronic state of this system. Especially, the Hall coefficient (RH) shows Curie-Weiss-type temperature d ependence, which is similar to that of high-T-c cuprates. In this paper, we study a Hubbard model on an anisotropic triangular lattice at half filling , which is an effective model of kappa-(BEDT-TTF)(2)X compounds. Based on t he fluctuation-exchange approximation, we calculate the resistivity (rho) a nd R-H by taking account of the vertex corrections for the current, which i s necessary for satisfying the conservation laws. Our theoretical results R (H)proportional toT(-1) and cot theta (H) proportional toT(2) explain the e xperimental behaviors well, which are unable to be reproduced by the conven tional Boltzmann transport approximation. Moreover, we extend the standard Eliashberg's transport theory and derive the more precise formula for the c onductivity, which becomes important at higher temperatures.