# Ballistic spin transport in the presence of interfaces with strong spin-orbit coupling

## TL;DR

This paper presents an analytical model to study how strong interfacial spin-orbit coupling affects ballistic spin transport phenomena, including spin-to-charge conversion and spin current swapping, in metallic bilayer systems.

## Contribution

It introduces a simple solvable model to analyze ISOC-induced spin transport effects, providing insights into spin-to-charge conversion and spin current swapping mechanisms.

## Key findings

- ISOC causes significant interface spin-loss.
- Spin galvanic effect mediated by ISOC generates in-plane charge currents.
- ISOC induces a generic spin current swapping effect.

## Abstract

The inversion symmetry breaking at the interface between different materials generates a strong interfacial spin-orbit coupling (ISOC) that may influence the spin and charge transport in hybrid structures. Here we use a simple analytically solvable model to study in the ballistic approximation various spin transport phenomena induced by ISOC in a bilayer metallic system. In this model a non-equilibrium steady state carrying a spin current is created by applying a spin dependent bias across the metallic junction. Physical observables are then calculated using the scattering matrix approach. In particular we calculate the absorption of the spin current at the interface (the interface spin-loss) and study the interface spin-to-charge conversion. The latter consists of an in-plane interface charge current generated by the spin dependent bias applied to the junction, which can be viewed as a spin galvanic effect mediated by ISOC. Finally we demonstrate that ISOC leads to an interfacial spin current swapping, that is, the "primary" spin current flowing through the spin-orbit active interface is necessarily accompanied with a "secondary' swapped spin current flowing along the interface and polarized in the direction perpendicular to that of the "primary" current. Using the exact spin continuity equation we relate the swapping effect to the intefacial spin-loss, and argue that this effect is generic and independent on the ballistic approximation used for specific calculations.