Thermoelectric effects in superconductor-ferromagnet tunnel junctions on europium sulfide

Abstract

Thermoelectric effects can be surprisingly large in superconductor-ferromagnet tunnel junctions when the superconductor is subject to a spin-splitting field. The spin splitting can be provided by an applied magnetic field, but can also be created by exchange coupling to a ferromagnetic insulator. Here, it is shown that thermoelectric effects in superconductor-ferromagnet tunnel junctions can be enhanced by boosting the spin splitting with an intrinsic exchange field provided by a ferromagnetic insulator. These findings could lead to more precise local electron thermometry or efficient microrefrigerators.