Spin Hall Effect of Excitons

TL;DR

This paper theoretically investigates the spin Hall effect of excitons in alkali halides and Cu₂O, showing how Berry curvature causes exciton trajectories that can be observed via polarized light emission.

Contribution

It demonstrates the origin of the exciton spin Hall effect from Berry curvature and proposes a method to observe it through emitted light polarization.

Findings

Spin Hall effect arises from Berry curvature in excitons.

Degeneracy lifting by exchange coupling induces nonzero Berry curvature.

Spatially polarized light reveals exciton trajectories.

Abstract

Spin Hall effect for excitons in alkali halides and in Cu_2O is investigated theoretically. In both systems, the spin Hall effect results from the Berry curvature in k space, which becomes nonzero due to lifting of degeneracies of the exciton states by exchange coupling. The trajectory of the excitons can be directly seen as spatial dependence of the circularly polarized light emitted from the excitons. It enables us to observe the spin Hall effect directly in the real-space time.