Spin-flip scattering and critical currents in ballistic half-metallic d-wave Josephson junctions

TL;DR

This paper investigates how spin-flip scattering and superconductor symmetry influence the Josephson effect in ballistic half-metallic junctions, revealing unique temperature dependencies and phase control mechanisms.

Contribution

It provides a new analytical expression for Andreev bound states and demonstrates control of 0-π transitions via magnetic misalignment at interfaces.

Findings

Temperature dependence of supercurrent varies with d-wave symmetry.

Magnetic misalignment can induce 0-π transitions.

Analytical formula for Andreev bound states derived.

Abstract

We analyze the dc Josephson effect in a ballistic superconductor/half-metal/superconductor junction by means of the Bogoliubov de Gennes equations. We study the role of spin-active interfaces and compare how different superconductor symmetries, including d-wave pairing, affect the Josephson current. We analyze the critical current as a function of junction width, temperature, and spin-flip strength and direction. In particular, we demonstrate that the temperature dependence of the supercurrent in the dxy symmetry case differs qualitatively from the s and dx2-y2 symmetries. Moreover, we have derived a general analytical expression for the Andreev bound-state energies that shows how one can either induce 0-{\pi} transitions or continuously change the ground-state phase of the junction by controlling the magnetic misalignment at the interfaces.