Intrinsic spin Nernst effect in spin-triplet superconductors

TL;DR

This paper theoretically explores the intrinsic spin Nernst effect in spin-triplet superconductors, revealing two main contributions and emphasizing the importance of considering thermoelectric spin supercurrents in nonunitary cases.

Contribution

It identifies and distinguishes between quasiparticle and supercurrent contributions to the spin Nernst effect in spin-triplet superconductors, highlighting the role of nonunitary pairing.

Findings

Quasiparticle contribution arises from Berry curvature in momentum space.

Supercurrent contribution can be significant in nonunitary superconductors.

Thermoelectric spin supercurrent must be considered in SNE evaluations.

Abstract

We theoretically investigate the intrinsic (impurity-independent) spin Nernst effect (SNE), a spin current generation perpendicular to temperature gradients, in spin-triplet superconductors. We show that, in these systems, the SNE consists of two distinct contributions: a direct quasiparticle contribution and an indirect supercurrent contribution. The quasiparticle contribution originates from the momentum space Berry curvature generated by spin-triplet Cooper pairs. The indirect contribution arises from a compensating supercurrent that cancels the bulk thermoelectric charge current. While this contribution vanishes when the condensate has no spin-polarization in momentum space, it can be comparable in magnitude to the quasiparticle contribution in nonunitary superconductors. These results demonstrate that thermoelectric spin supercurrent must be explicitly accounted for when evaluating the SNE in nonunitary superconductors.