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

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.