Spin-current in generic hybrid structures due to interfacial spin-orbit scattering

TL;DR

This paper reveals that hybrid structures inherently generate a pure spin-current parallel to the interface when a charge current is injected, due to interfacial spin-orbit coupling caused by broken mirror symmetry.

Contribution

It provides a general analytical condition for spin-current generation at interfaces and explicitly calculates the effect using two models, including the influence of Andreev reflection with superconductors.

Findings

Pure spin-current flows parallel to the interface in hybrid structures.

Broken mirror symmetry induces spin-orbit coupling that deflects electrons.

Andreev reflection modifies the spin-current in superconducting scenarios.

Abstract

We demonstrate a general principle that hybrid structures of any sort inevitably will give rise to a pure spin-current flowing parallel to the interface region when a charge-current is injected. This stems from the broken mirror symmetry near the interface which gives rise to spin-orbit coupling that deflects incoming electrons in a spin-discriminating fashion. We establish a general analytical condition for the appearance of this effect, and calculate the transverse spin-current explicitly using two different models. In addition, we investigate how the process of Andreev-reflection influences this phenomenon in the scenario where one of the materials is superconducting.