Spin Hall effect at interfaces between HgTe/CdTe quantum wells and metals

We study the spin-dependent transmission through interfaces between a HgTe/CdTe quantum well (QW) and a metal for both the normal metal and the superconducting cases. Interestingly, we discover a type of spin Hall effect at these interfaces that happens to exist even in the absence of structure and bulk inversion asymmetry within each subsystem (i.e., the QW and the metal). Thus, this is a pure boundary spin Hall effect which can be directly related to the existence of exponentially localized edge states at the interface. We demonstrate how this effect can be measured and functionalized for an all-electric spin injection into normal metal leads.