Enhancement of Spin Polarization by Spin Anisotropic Scattering

Highly spin-polarized current is desirable for spintronics, but spin is often required to be injected from a spin source to another material via an interface. This often significantly reduces spin polarization of the current. Some materials can scatter spin-up and spin-down electrons very differently, and they can be utilized to create a spin-filtering interface; this actually enhances spin polarization. At a normal metal/superconductor interface, Andreev reflection occurs.~ This can be utilized to measure spin polarization of the normal metal.~ In this work, we theoretically calculate the Andreev reflection spectroscopy of an interface with spin anisotropic scattering. We will show that the Andreev spectra is symmetrical as a function of the bias voltage, and that the spin polarization value can still be determined. With a proper interface (with spin filtering), the spin polarization value can be significantly enhanced, and this will aid in an enhanced performance of spintronic devices.