Renormalization group analysis of thermal transport in the disordered Fermi liquid

TL;DR

This paper develops a renormalization group approach combining gravitational potentials and nonlinear sigma models to analyze thermal transport in disordered Fermi liquids, demonstrating the Wiedemann-Franz law's validity at low temperatures.

Contribution

It introduces a novel theoretical framework merging gravitational potentials with RG analysis for thermal transport in disordered Fermi liquids, accounting for quantum corrections.

Findings

Quantum corrections lead to non-analytic behavior in thermal conductivity.

The Wiedemann-Franz law remains valid at low temperatures despite disorder and interactions.

The gravitational potentials acquire independent RG flow, preserving energy conservation constraints.

Abstract

We present a detailed study of thermal transport in the disordered Fermi liquid with short-range interactions. At temperatures smaller than the impurity scattering rate, i.e., in the diffusive regime, thermal conductivity acquires non-analytic quantum corrections. When these quantum corrections become large at low temperatures, the calculation of thermal conductivity demands a theoretical approach that treats disorder and interactions on an equal footing. In this paper, we develop such an approach by merging Luttinger's idea of using gravitational potentials for the analysis of thermal phenomena with a renormalization group calculation based on the Keldysh nonlinear sigma model. The gravitational potentials are introduced in the action as auxiliary sources that couple to the heat density. These sources are a convenient tool for generating expressions for the heat density and its correlation function from the partition function. Already in the absence of the gravitational potentials, the nonlinear sigma model contains several temperature-dependent renormalization group charges. When the gravitational potentials are introduced into the model, they acquire an independent renormalization group flow. We show that this flow preserves the phenomenological form of the correlation function, reflecting its relation to the specific heat and the constraints imposed by energy conservation. The main result of our analysis is that the Wiedemann-Franz law holds down to the lowest temperatures even in the presence of disorder and interactions and despite the quantum corrections that arise for both the electric and thermal conductivities.