Non-Fermi-liquid metals in low dimensions

Abstract

In low-dimensional metals the presence of massless excitations may lead to a breakdown of the Landau Fermi-liquid description, which successfully applies to higher- dimensional metals. This breakdown is mirrored by infrared divergences which plague the perturbative treatment of models for low-dimensional metals, despite the fact that the metallic phase is a stable liquid phase of the matter. However, the very condition of stability of the system implies exact cancellations among the singular terms in the response functions, controlled by additional Ward identities, which must be considered besides the standard Ward identities related to the conservation of the total particle and spin density. The combined use of renormalization group and of these Ward identities allows for the closure of the renormalization-group equations, leading to the description of the asymptotic (infrared) behavior of the low-dimensional metal.