Spin-current coherence peak in superconductor/magnet junctions

TL;DR

This paper reports the observation of a coherence peak effect in a superconductor induced by a thermal spin current, demonstrated through inverse spin Hall effects near the superconducting transition temperature.

Contribution

It provides experimental evidence of a coherence peak effect in superconductor/magnet junctions driven by thermal spin currents, expanding understanding of spin transport in superconductors.

Findings

Large enhancement of spin Seebeck voltage near Tc

Sign of voltage opposite to vortex Nernst effect

Consistent with coherence peak effect in NbN

Abstract

Coherence peak effects in a superconductor induced by a thermal spin current are reported. We measured inverse spin Hall effects induced by spin injection from a ferrimagnetic insulator Y$_3$Fe$_5$O$_{12}$ into a superconductor NbN using longitudinal spin Seebeck effects. In the vicinity of the superconducting transition temperature of the NbN, a large enhancement of the spin Seebeck voltage is observed, whose sign is opposite to that for the vortex Nernst effect, but is consistent with a calculation for a coherence peak effect in the superconductor NbN.