Electronic susceptibilities in systems with anisotropic Fermi surfaces

TL;DR

This paper investigates how anisotropic Fermi surfaces influence low-temperature spin and charge susceptibilities, revealing a generic $T \, \log T$ dependence and more singular behaviors, with implications for quasi-two-dimensional materials.

Contribution

It introduces a detailed analysis of susceptibility behavior in anisotropic 2D systems, highlighting the role of Fermi surface inflection points and their impact on temperature dependence.

Findings

Susceptibilities exhibit a $T \log T$ dependence due to inflection points.

More singular behavior, $T^{3/4} \log T$, is also possible.

Applications discussed for quasi-2D materials.

Abstract

The low temperature dependence of the spin and charge susceptibilities of an anisotropic electron system in two dimensions is analyzed. It is shown that the presence of inflection points at the Fermi surface leads, generically, to a $ T \log T $ dependence, and a more singular behavior, $\chi \sim T ^{3/4} \log T$, is also possible. Applications to quasi two-dimensional materials are discussed.