Tunability of Andreev levels in a spin-active Ising superconductor/half-metal Josephson junction

Abstract

We study the Andreev levels, supercurrent and tunnelling conductance in a clean Ising superconductor (ISC)/half-metal (HM)/ISC Josephson junction (JJ) with spin-active interfaces using Bogoliubov–de Gennes equations. We theoretically demonstrate the effect of spin mixing, spin flipping processes and spin–orbit coupling (SOC) of the ISC on Andreev bound states spectra, the current phase relation and tunnelling conductance in a transparent and opaque barrier limit. We witness an additional splitting of the Andreev levels due to the SOC of the ISC and transition for different barrier magnetic moments. Also, different φ-junctions can be achieved by tuning the strength of the barrier magnetic moment and spin mismatch angle. Moreover, a possible transition can also be achieved for a SOC stronger than the chemical potential of the ISC using suitable control parameters. The tunnelling conductance is found to be dependent on the spin mismatch angle. A finite subgap conductance is also observed, indicating different probabilities of Andreev reflected electrons and holes in the presence of SOC. Furthermore, anomalous Andreev levels are observed for different HM length scales, signifying their role in the tunability of the φ-phase JJ.