Pairing symmetry conversion by spin-active interfaces in superconducting junctions

TL;DR

This paper investigates how spin-active interfaces in superconductor-normal metal junctions can convert pairing symmetry, revealing a critical interface resistance where odd-frequency pairing persists while even-frequency pairing vanishes, and suggests experimental observation methods.

Contribution

It demonstrates the existence of a critical interface resistance that causes a transition from even- to odd-frequency pairing in superconductor-normal metal junctions with spin-active interfaces.

Findings

At a critical interface resistance, even-frequency pairing disappears.

Odd-frequency pairing remains finite at the critical resistance.

Proposes an experimental method to observe odd-frequency pairing.

Abstract

We study the proximity-induced superconducting correlations in a normal metal connected to a superconductor when the interface between them is spin-active and the normal metal is ballistic or diffusive. Remarkably, for any interface spin polarization there is a critical interface resistance, above which the conventional even-frequency proximity component vanishes completely at the chemical potential, while the odd-frequency component remains finite. We propose a way to unambiguously observe the odd-frequency component.