Phase Dependent Thermopower in Andreev Interferometers

TL;DR

This study measures the thermopower in mesoscopic Andreev interferometers, revealing phase-dependent oscillations influenced by magnetic flux and temperature, with effects varying based on sample topology.

Contribution

First detailed measurement of phase-dependent thermopower in hybrid superconductor-normal metal interferometers, highlighting topology-dependent symmetry effects.

Findings

Thermopower oscillates with magnetic flux, period h/2e.

Maximum thermopower occurs around 0.14 K.

Oscillation symmetry depends on sample topology.

Abstract

We report measurements of the thermopower S of mesoscopic Andreev interferometers, which are hybrid loops with one arm fabricated from a superconductor (Al), and one arm from a normal metal (Au). S depends on the phase of electrons in the interferometer, oscillating as a function of magnetic flux with a period of one flux quantum (= h/2e). The magnitude of S increases as the temperature T is lowered, reaching a maximum around T = 0.14 K, and decreases at lower temperatures. The symmetry of S oscillations with respect to magnetic flux depends on the topology of the sample.