Spin conductance in SNN junctions with non-centrosymmetric superconductors

TL;DR

This paper investigates spin conductance in SNN junctions with mixed s-wave and p-wave superconductors, providing methods to distinguish superconductor types and revealing conductance differences due to mixed pair potentials.

Contribution

It introduces a novel approach to identify superconductor pairing symmetries using spin conductance measurements in SNN junctions.

Findings

Spin sectors satisfy independent equations, simplifying calculations.

Presence of both s-wave and p-wave components causes spin-dependent conductance differences.

A double junction setup can clearly differentiate superconductor types.

Abstract

An SNN-junction in which the superconducting potential is a mixture between s-wave and p-wave potentials is investigated using the Usadel equation equipped with Tanaka-Nazarov boundary conditions. The article provides several ways to distinguish between s + chiral and s + helical p-wave superconductors and a way to determine whether a superconductor has a mixed pair potential. Thus, it is of great importance in the determination of the pair potential of superconductors. It is shown that the different spin sectors satisfy independent equations and can thus be calculated separately even if the d-vector depends on the direction of momentum. This greatly simplifies the equations to be solved. It was found that a difference in conductance for sectors with opposite spins arises if both an s-wave and a p-wave component is present, even in the absence of a magnetic field. The results are confirmed by calculations in the ballistic regime. It is shown that the spin conductance for s + chiral p-wave and s + helical p-wave junctions is qualitatively similar. A setup containing two SN junctions is shown to give a clear difference between the two types of superconductivity.