The symmetry of phase-coherent thermopower oscillations in Andreev interferometers

TL;DR

This study investigates the magnetic flux-dependent thermopower oscillations in diffusive Andreev interferometers, revealing geometry-dependent symmetry properties linked to supercurrent distribution, and compares experimental findings with theoretical predictions.

Contribution

It provides new insights into the symmetry behavior of thermopower oscillations in hybrid superconducting-normal metal loops, highlighting the role of geometry and supercurrent distribution.

Findings

Thermopower oscillates with magnetic flux, showing symmetry or antisymmetry depending on geometry.

Symmetry of thermopower oscillations is related to supercurrent distribution.

Experimental results align with recent theoretical models.

Abstract

We study the thermopower of diffusive Andreev interferometers, which are hybrid loops with one normal-metal arm and one superconducting arm. The thermopower oscillates as a function of the magnetic flux through the loop with a fundamental period corresponding to one flux quantum $\Phi_0=h/2e$. Unlike the electrical resistance oscillations and the thermal resistance oscillations, which are always symmetric with respect to the magnetic field, the symmetry of the thermopower oscillations can be either symmetric or antisymmetric depending on the geometry of the sample. We also observe that the symmetry of the thermopower oscillations is related to the distribution of the supercurrent between the normal-metal/superconductor interfaces. We compare our experimental results with recent theoretical work.