Non-Relativistic Spin-Orbit Interaction in Triplet Superconductors: Edelstein Effect and Spin Pumping by Electric Fields

TL;DR

This paper uncovers a non-relativistic spin-orbit coupling mechanism in triplet superconductors that enables electric-field-induced spin polarization and spin current generation without relativistic effects.

Contribution

It introduces a novel non-relativistic spin-orbit interaction in triplet superconductors, linking spin textures to electric field effects and spin current manipulation.

Findings

Triplet order parameter induces wave-vector-dependent spin textures.

Electric fields can generate spin polarization in p-wave superconductors.

Proposed scheme for nonlinear DC spin current generation using electric near fields.

Abstract

Non-relativistic momentum-dependent spin splitting, as observed in collinear altermagnets and non-collinear $p$-wave magnets, provides exciting avenues for controlling spin dynamics. Here, we reveal a distinct form of non-relativistic ``spin-orbit coupling" in triplet superconductors by demonstrating that the triplet order parameter induces a wave-vector-dependent spin texture of Bogoliubov quasiparticles, thereby entangling their orbital and spin motions. Even in the absence of relativistic spin-orbit coupling, this intertwining of spin and orbital motion allows an electric field to generate spin polarization in a $p$-wave superconductor -- that is, an Edelstein effect. Building on this mechanism, we propose an efficient scheme for the nonlinear generation of a DC spin current via electric near fields, driven by AC spin polarization and electron velocity. This general principle offers a powerful route for generating and manipulating spin currents in unconventional superconductors.