Spin current and spin accumulation near a Josephson junction between a singlet and triplet superconductor

TL;DR

This paper analyzes the spin current and spin accumulation near a Josephson junction between singlet and triplet superconductors, providing theoretical calculations and symmetry insights into these phenomena.

Contribution

It introduces a comprehensive theoretical framework for understanding spin-related effects in singlet-triplet Josephson junctions, including calculations of tunneling current, spin accumulation, and spin current.

Findings

Quantitative expressions for spin current and accumulation are derived.

Symmetry considerations explain the existence and behavior of these quantities.

Physical interpretation via Andreev states is provided.

Abstract

We consider a Josephson junction with an arbitrary transmission coefficient $\mathcal{D}$ between a singlet and a triplet superconductor with the latter order parameter characterized by a d-vector of the form ($k_x\hat{y}-k_y\hat{x}$). Various quantities such as the tunnelling current, spin accumulation, and spin current are calculated via the quasiclassical Green's functions. We also present a symmetry argument on the existence of these quantities and their dependencies on the phase difference across the junction. A physical picture is also given in terms of the Andreev states near the junction.