Observation of thermoelectric currents in high-field superconductor-ferromagnet tunnel junctions

TL;DR

This paper reports the experimental detection of significant thermoelectric currents in superconductor-ferromagnet tunnel junctions under high magnetic fields, confirming theoretical predictions and demonstrating spin-heat coupling.

Contribution

It provides the first experimental evidence of thermoelectric effects in high-field superconductor-ferromagnet junctions, highlighting the role of spin-dependent particle-hole symmetry breaking.

Findings

Thermoelectric signals are due to spin-dependent particle-hole symmetry lifting.

Maximum Seebeck coefficient is about -100 μV/K, larger than in metallic structures.

Results confirm the coupling of spin and heat transport in high-field superconductors.

Abstract

We report on the experimental observation of thermoelectric currents in superconductor-ferromagnet tunnel junctions in high magnetic fields. The thermoelectric signals are due to a spin-dependent lifting of particle-hole symmetry, and are found to be in excellent agreement with recent theoretical predictions. The maximum Seebeck coefficient inferred from the data is about $-100~\mathrm{\mu V/K}$, much larger than commonly found in metallic structures. Our results directly prove the coupling of spin and heat transport in high-field superconductors.