Spin-density-wave instabilites for imperfectly nested fermi surfaces : application to bedt-ttf salts

Abstract

We discuss criteria for determining the optimal nesting vector from the maximum of the zero-field susceptibility for imperfectly nested Fermi surfaces. In particular, we present results for some of the bis(ethylenedithio) tetrathiafulvalene charge-transfer salts, a family of quasi-two-dimensional organic conductors. The criteria proposed gives better nesting than the previous criteria that has been applied to the tetramethyltetraselenafulvalene family, in which the nesting vector translates a point of inflection on the Fermi surface. We discuss the nesting vectors deduced, and consequences for Fermi-surface reconstruction and low-temperature behavior.