Spin polarization of the quantum spin Hall edge states

TL;DR

This paper demonstrates experimental evidence of spin polarization in quantum spin Hall edge states using HgTe quantum wells, combining quantum and metallic spin Hall effects for all-electrical spin detection.

Contribution

It introduces a novel all-electrical method to confirm spin polarization in quantum spin Hall edge states through combined quantum and metallic spin Hall transport in HgTe nanostructures.

Findings

Successful detection of spin polarization in quantum spin Hall edge states.

Integration of quantum and metallic spin Hall effects in a single device.

All-electrical measurement of spin polarization achieved.

Abstract

While the helical character of the edge channels responsible for charge transport in the quantum spin Hall regime of a two-dimensional topological insulator is by now well established, an experimental confirmation that the transport in the edge channels is spin-polarized is still outstanding. We report experiments on nanostructures fabricated from HgTe quantum wells with an inverted band structure, in which a split gate technique allows us to combine both quantum spin Hall and metallic spin Hall transport in a single device. In these devices, the quantum spin Hall effect can be used as a spin current injector and detector for the metallic spin Hall effect, and vice versa, allowing for an all-electrical detection of spin polarization.