Coherent Thermoelectric Effects in Mesoscopic Andreev Interferometers

TL;DR

This paper explores thermoelectric effects in mesoscopic Andreev interferometers, revealing phase-dependent oscillations in conductance and thermopower, with symmetry properties influenced by contact dwell time asymmetries.

Contribution

It uncovers how phase differences and dwell time asymmetries affect thermoelectric responses, highlighting novel phase-dependent thermopower behaviors in mesoscopic systems.

Findings

Thermal and charge conductance ratio oscillates with phase difference.

Large thermopower occurs with dwell time asymmetry, odd in phase.

Sample-dependent thermopower is even in phase when dwell times are symmetric.

Abstract

We investigate thermoelectric transport through Andreev interferometers. We show that the ratio of the thermal and the charge conductance exhibits large oscillations with the phase difference $\phi$ between the two superconducting contacts, and that the Wiedemann-Franz law holds only when $\phi=\pi$. A large average thermopower furthermore emerges whenever there is an asymmetry in the dwell times to reach the superconducting contacts. When this is the case, the thermopower is odd in $\phi$. In contrast, when the average times to reach either superconducting contact are the same, the average thermopower is zero, however mesoscopic effects (analogous to universal conductance fluctuations) lead to a sample-dependent thermopower which is systematically even in $\phi$.