Josephson current and Andreev states in superconductor-half metal-superconductor heterostructures

TL;DR

This paper presents a microscopic theory of the Josephson effect and Andreev bound states in superconductor-half metal-superconductor junctions, highlighting the role of spin-flip scattering in generating triplet pairing and influencing supercurrent behavior.

Contribution

It provides a detailed non-perturbative analysis of Josephson current and Andreev states considering arbitrary interface transmissions and spin-flip scattering, which is novel in the context of half-metallic heterostructures.

Findings

Supercurrent is mediated by triplet pairing states due to spin-flip scattering.

The Josephson current and Andreev states depend critically on spin-flip scattering strength.

Rich variety of behaviors predicted, testable in future experiments.

Abstract

We develop a detailed microscopic theory describing dc Josephson effect and Andreev bound states in superconducting junctions with a half-metal. In such systems the supercurrent is caused by triplet pairing states emerging due to spin-flip scattering at the interfaces between superconducting electrodes and the half-metal. For sufficiently clean metals we provide a detailed non-perturbative description of the Josephson current at arbitrary transmissions and spin-flip scattering parameters for both interfaces. Our analysis demonstrates that the behavior of both the Josephson current and Andreev bound states crucially depends on the strength of spin-flip scattering showing a rich variety of features which can be tested in future experiments.