Spin-dependent Andreev reflection in spin-orbit coupled systems by breaking time-reversal symmetry

TL;DR

This paper theoretically investigates how breaking time-reversal symmetry in spin-orbit coupled systems influences spin-dependent Andreev reflection, revealing spin-dependent transport phenomena controlled by incident angle and competing mass terms.

Contribution

It introduces a theoretical framework for understanding spin-dependent Andreev reflection in systems with broken time-reversal symmetry and tunable band gaps.

Findings

Spin-dependent Andreev reflection probabilities vary with incident electron spin.

The incident angle of electrons influences the spin-dependence of transport.

Competing mass terms in the system's energy landscape cause differences in Andreev reflection.

Abstract

We study theoretically the differential conductance at a junction between a time reversal symmetry broken spin orbit coupled system with a tunable band gap and a superconductor. We look for spin-dependent Andreev reflection (i.e, sub-gap transport) and show that when various mass terms compete in energy, there is substantial difference of Andreev reflection probability depending on the spin of the incident electron. We further analyze the origin of such spin-dependence and show how the incident angle of the electrons controls the spin-dependence of the transport.