Josephson current in ballistic heterostructures with spin-active interfaces

TL;DR

This paper presents a microscopic theory of the dc Josephson effect in ballistic SNS heterostructures with spin-active interfaces, revealing how spin-dependent scattering influences supercurrent and junction states.

Contribution

It introduces a comprehensive microscopic framework linking Andreev levels to Josephson current in systems with spin-active interfaces, highlighting effects of spin-mixing and magnetization.

Findings

Identification of conditions for pi-junction states.

Resonant supercurrent enhancement in gate-controlled nanojunctions.

Strong influence of spin-dependent scattering on supercurrent behavior.

Abstract

We develop a general microscopic theory of dc Josephson effect in hybrid SNS structures with ballistic electrodes and spin-active NS interfaces. We establish a direct relation between the spectrum of Andreev levels and the Josephson current which contains complete information about non-trivial interplay between Andreev reflection and spin-dependent interface scattering. The system exhibits a rich structure of properties sensitive to spin-dependent barrier transmissions, spin-mixing angles, relative magnetization orientation of interfaces and the kinematic phase of scattered electrons. We analyze the current-phase relations and identify the conditions for the presence of a pi-junction state in the systems under consideration. We also analyze resonant enhancement of the supercurrent in gate-voltage-driven nanojunctions. As compared to the non-magnetic case, this effect can be strongly modified by spin-dependent scattering at NS interfaces.