Thermal conductance of Andreev interferometers

TL;DR

This paper calculates the thermal conductance of diffusive Andreev interferometers, revealing how superconducting proximity effects suppress but do not eliminate thermal conductance at low temperatures, with results matching recent experimental observations.

Contribution

It provides a theoretical analysis of thermal conductance in Andreev interferometers, highlighting the non-vanishing conductance at zero temperature and its dependence on interface resistance and geometry.

Findings

$G^T$ saturates at finite value as $T o 0$

Suppression of $G^T$ is linked to density of states reduction

$G^T$ exhibits strong nonlinearity with thermal current

Abstract

We calculate the thermal conductance $G^T$ of diffusive Andreev interferometers, which are hybrid loops with one superconducting arm and one normal-metal arm. The presence of the superconductor suppresses $G^T$; however, unlike a conventional superconductor, $G^T/G^T_N$ does not vanish as the temperature $T\to0$, but saturates at a finite value that depends on the resistance of the normal-superconducting interfaces, and their distance from the path of the temperature gradient. The reduction of $G^T$ is determined primarily by the suppression of the density of states in the proximity-coupled normal metal along the path of the temperature gradient. $G^T$ is also a strongly nonlinear function of the thermal current, as found in recent experiments.