Spontaneous Edge Accumulation of Spin Currents in Finite-Size Two-Dimensional Diffusive Spin-Orbit Coupled SFS Heterostructures

TL;DR

This paper theoretically demonstrates that finite-size two-dimensional SFS heterostructures with spin-orbit interactions spontaneously accumulate spin currents at their edges due to broken symmetries, independent of specific ISOI types or exchange orientations.

Contribution

It reveals the robust, spontaneous edge spin accumulation in 2D SFS junctions with spin-orbit coupling, a phenomenon previously unreported in such systems.

Findings

Spontaneous edge spin currents occur at the corners of the F wire.

Edge phenomena are robust against variations in ISOI types and exchange field orientations.

Spin currents can exist without accompanying charge supercurrents, modulated by the superconducting phase difference.

Abstract

We theoretically study spin and charge currents through finite-size two-dimensional $s$-wave superconductor/uniform ferromagnet/s-wave superconductor (SFS) junctions with intrinsic spin-orbit interactions (ISOIs) using a quasiclassical approach. Considering experimentally realistic parameters, we demonstrate that the combination of spontaneously broken time-reversal symmetry and lack of inversion symmetry can result in spontaneously accumulated spin currents at the edges of finite-size two-dimensional magnetic SF hybrids. Due to the spontaneous edge spin accumulation, the corners of the F wire host the maximum spin current density. We further reveal that this type edge phenomena are robust and independent of either the actual type of ISOIs or exchange field orientation. Moreover, we study spin current-phase relations in these diffusive spin-orbit coupled SFS junctions. Our results unveil net spin currents, not accompanied by charge supercurrent, that spontaneously accumulate at the sample edges through a modulating superconducting phase difference. Finally, we discuss possible experimental implementations to observe these edge phenomena.