Nesting of the Fermi surface and the wave-vector-dependent susceptibility in quasi-one-dimensional electron systems

Abstract

The wave-vector dependence of the susceptibility in quasi-one-dimensional systems is studied theoretically without and with external magnetic field in the perpendicular direction. We show that the wave-vector-dependent susceptibility has a two-step plateaulike structure in the absence of the magnetic field, when the warping of the Fermi surface caused by the $\ensuremath{\mp}2{\ensuremath{\tau}}_{3}\text{ }\text{sin}[3({k}_{y}\ensuremath{\mp}\ensuremath{\phi})]$ term, which breaks the reflection symmetry with respect to the most conducting chain, is larger than the critical value. The susceptibility is shown to have the plateaulike maximum in the small region in the wave vector at the edge of the lower plateau. We discuss the importance of the plateaulike maximum for the the field-induced spin density wave states in quasi-one-dimensional systems, such as the organic conductors ${(\text{TMTSF})}_{2}{\text{PF}}_{6}$ and ${(\text{TMTSF})}_{2}{\text{ClO}}_{4}$.