Thermal transport in granular metals

TL;DR

This paper investigates how electron-electron interactions affect thermal transport in granular metals with high tunnel conductance, revealing a violation of the Wiedemann-Franz law and differing suppression of thermal versus electrical conductivity.

Contribution

It provides a theoretical calculation of thermal conductivity in granular metals considering interactions, highlighting the violation of the Wiedemann-Franz law.

Findings

Interaction effects suppress thermal conductivity less than electrical conductivity

Wiedemann-Franz law is violated in granular metals at high tunnel conductance

Thermal transport behavior differs from classical expectations due to electron-electron interactions

Abstract

We study the electron thermal transport in granular metals at large tunnel conductance between the grains, $g_T \gg 1$ and not too low a temperature $T > g_T\delta$, where $\delta$ is the mean energy level spacing for a single grain. Taking into account the electron-electron interaction effects we calculate the thermal conductivity and show that the Wiedemann-Franz law is violated for granular metals. We find that interaction effects suppress the thermal conductivity less than the electrical conductivity.