Thermodynamics of a Fermi liquid beyond the low-energy limit

TL;DR

This paper analyzes the temperature dependence of specific heat and spin susceptibility in 2D Fermi liquids beyond weak interactions, showing linear behavior governed by Fermi liquid theory and relating it to backscattering amplitudes.

Contribution

It extends Fermi liquid theory to describe non-analytic temperature dependences beyond weak coupling using the Luttinger-Ward formalism.

Findings

Linear temperature dependence of C(T)/T and χ_s(T) confirmed.

Universal relation of temperature dependences to backscattering amplitudes.

Agreement with recent experiments on 2D 3He monolayers.

Abstract

We consider the non-analytic temperature dependences of the specific heat coefficient, C(T)/T, and spin susceptibility, \chi_{s} (T), of 2D interacting fermions beyond the weak-coupling limit. We demonstrate within the Luttinger-Ward formalism that the leading temperature dependences of C(T)/T and \chi_s (T) are linear in T, and are described by the Fermi liquid theory. We show that these temperature dependences are universally determined by the states near the Fermi level and, for a generic interaction, are expressed via the spin and charge components of the exact backscattering amplitude of quasi-particles. We compare our theory to recent experiments on monolayers of 3He.