Spin-current in generic hybrid structures due to interfacial spin-orbit scattering

We demonstrate a general principle that hybrid structures of any sort inevitably will give rise to a pure spin-current flowing parallel to the interface region when a charge-current is injected. This stems from the broken mirror symmetry near the interface which gives rise to spin-orbit coupling that deflects incoming electrons in a spin-discriminating fashion. We establish a general analytical condition for the appearance of this effect, and calculate the transverse spin-current explicitly using two different models. In addition, we investigate how the process of Andreev-reflection influences this phenomenon in the scenario where one of the materials is superconducting.