Two-loop renormalization of the Finkel'stein theory: The specific heat

TL;DR

This paper calculates the two-loop renormalization of the specific heat in an interacting disordered electron system with broken time reversal symmetry, revealing differences in anomalous dimensions beyond one-loop.

Contribution

It provides the two-loop anomalous dimension for the specific heat in a disordered electron system with broken symmetries, extending previous one-loop results.

Findings

Two-loop anomalous dimension for specific heat derived

Differences in anomalous dimensions beyond one-loop identified

Application to metal-insulator transition in 2+ε dimensions

Abstract

We explore the two-loop renormalization of the specific heat for an interacting disordered electron system in the case of broken time reversal symmetry. Within the nonlinear sigma model approach we derive the two-loop result for the anomalous dimension which controls scaling of the specific heat with temperature. As an example, we elaborate the metal-insulator transition in $d=2+\epsilon$ dimensions for the case of broken time reversal and spin rotational symmetries and in the presence of Coulomb interaction. In this situation scaling of the specific heat is determined by the anomalous dimension of the Finkel'stein operator which is the eigen operator of the renormalization group complementary to the eigen operator corresponding to the second moment of the local density of states. We find that the absolute values of the anomalous dimensions of these operators differ beyond one-loop approximation contrary to the noninteracting case.