Spin-polarized specular Andreev reflections in altermagnets

The authors theoretically show here that the characteristic spin-split bands of altermagnets give rise to distinctive spin polarized specular Andreev reflections at altermagnet--superconductor interfaces. By utilizing this feature, they propose a device that integrates the functions of both a Cooper pair splitter and a spin beam splitter, thereby creating energy entangled electron pairs. The positive nonlocal conductance and the positive noise cross-correlation are unambiguous signatures of specular Andreev reflections in the proposed device.