Anomalous currents and spontaneous vortices in spin-orbit coupled superconductors

TL;DR

This paper introduces a mechanism where spin-orbit interactions near magnetic inclusions in superconductors generate supercurrents and vortices without external magnetic fields, explaining phenomena like magnetic memory effects.

Contribution

It proposes a novel spin-orbit coupling mechanism for supercurrent generation and vortex formation in superconductors with magnetic inclusions, supported by a Ginzburg-Landau model.

Findings

Can induce supercurrents without external magnetic fields.

Can generate vortices through inclusion distribution.

Explains magnetic memory effects in certain materials.

Abstract

We propose a mechanism which can generate supercurrents in spin-orbit coupled superconductors with charged magnetic inclusions. The basic idea is that through spin-orbit interaction, the in-plane electric field near the edge of each inclusion appears to the electrons as an effective spin-dependent gauge field; if Cooper pairs can be partially spin polarized, then each pair experiences a nonzero net transverse pseudo-gauge field. We explore the phenomenology of our mechanism within a Ginzburg-Landau theory, with parameters determined from a microscopic model. Depending on parameters, our mechanism can either enhance or reduce the total magnetization upon superconducting condensation. Given an appropriate distribution of inclusions, we show how our mechanism can generate superconducting vortices without any applied orbital magnetic field. Our mechanism can produce similar qualitative behavior to the ``magnetic memory effect'' observed in 4Hb-TaS$_2$. However, the magnitude of the effect in that material seems larger than our model can naturally explain.