Nonlocal Thermoelectric Effects and Nonlocal Onsager Relations in a Three-Terminal Proximity-Coupled Superconductor-Ferromagnet Device

TL;DR

This paper investigates nonlocal thermoelectric effects in a three-terminal superconductor-ferromagnet device, revealing large effects due to spin filtering and phase shifts, and establishing nonlocal Onsager relations in quantum coherent systems.

Contribution

It demonstrates the existence of significant nonlocal thermoelectric effects and formulates nonlocal Onsager relations in a three-terminal ferromagnet-superconductor heterostructure.

Findings

Large nonlocal thermoelectric effects predicted with spin filtering.

Nonlocal Onsager relations hold in quantum coherent heterostructures.

Effects observed in both clean and disordered systems.

Abstract

We study thermal and charge transport in a three-terminal setup consisting of one superconducting and two ferromagnetic contacts. We predict that the simultaneous presence of spin filtering and of spin- dependent scattering phase shifts at each of the two interfaces will lead to very large nonlocal thermo- electric effects both in clean and in disordered systems. The symmetries of thermal and electric transport coefficients are related to fundamental thermodynamic principles by the Onsager reciprocity. Our results show that a nonlocal version of the Onsager relations for thermoelectric currents holds in a three-terminal quantum coherent ferromagnet-superconductor heterostructure including a spin-dependent crossed Andreev reflection and coherent electron transfer processes.