Electronic susceptibilities in systems with anisotropic Fermi surfaces

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.