Long-Range Spin-Triplet Correlations and Edge Spin Currents in Diffusive Spin-Orbit Coupled SNS Hybrids with a Single Spin-Active Interface

TL;DR

This paper theoretically demonstrates how intrinsic spin-orbit interactions and a single spin-active interface in diffusive S/N/S structures generate long-range spin-triplet correlations and edge spin currents, independent of external fields.

Contribution

It introduces a SU(2) gauge symmetry approach to reveal edge spin currents and triplet correlations in spin-orbit coupled superconductor/normal-metal hybrids with a single spin-active interface.

Findings

Maximum singlet-triplet conversion occurs at the N wire corners.

Edge spin currents can be observed without accompanying charge currents.

These phenomena are robust, field-independent, and insensitive to interface spin orientation.

Abstract

Utilizing a SU(2) gauge symmetry technique in the quasiclassical diffusive regime, we theoretically study finite-sized two-dimensional intrinsic spin-orbit coupled superconductor/normal-metal/superconductor (S/N/S) hybrid structures with a single spin-active interface. We consider intrinsic spin-orbit interactions (ISOIs) that are confined within the N wire and absent in the s-wave superconducting electrodes (S). Using experimentally feasible parameters, we demonstrate that the coupling of the ISOIs and spin moment of the spin-active interface results in maximum singlet-triplet conversion and accumulation of spin current density at the corners of the N wire nearest the spin-active interface. By solely modulating the superconducting phase difference, we show how the opposing parities of the charge and spin currents provide an effective venue to experimentally examine pure edge spin currents not accompanied by charge currents. These effects occur in the absence of externally imposed fields, and moreover are insensitive to the arbitrary orientations of the interface spin moment. The experimental implementation of these robust edge phenomena are also discussed.