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

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-π transitions or continuously change the ground-state phase of the junction by controlling the magnetic misalignment at the interfaces.