Experimental Observation of the Spin-Hall Effect in a Two-Dimensional Spin-Orbit Coupled Semiconductor System

TLDR

In equilibrium, the angular momenta of the spin‑orbit split heavy‑hole states lie in the plane of the 2D layer. The authors used a 2D hole layer in a p‑n junction light‑emitting diode with a coplanar geometry that permits angle‑resolved polarization detection at opposite edges, and performed microscopic quantum transport calculations that show only a weak disorder effect, supporting an intrinsic spin‑Hall conductance description. The experiment observed a spin‑Hall effect in a 2D hole system with spin‑orbit coupling, where applying an electric field across the channel produced a nonzero out‑of‑plane angular‑momentum component whose sign depends on the field direction and is opposite at the two edges, and microscopic transport calculations indicate that disorder has only a weak effect, supporting an intrinsic spin‑Hall conductance description.

Abstract

We report the experimental observation of the spin-Hall effect in a 2D hole system with spin-orbit coupling. The 2D hole layer is a part of a p-n junction light-emitting diode with a specially designed coplanar geometry which allows an angle-resolved polarization detection at opposite edges of the 2D hole system. In equilibrium the angular momenta of the spin-orbit split heavy-hole states lie in the plane of the 2D layer. When an electric field is applied across the hole channel, a nonzero out-of-plane component of the angular momentum is detected whose sign depends on the sign of the electric field and is opposite for the two edges. Microscopic quantum transport calculations show only a weak effect of disorder, suggesting that the clean limit spin-Hall conductance description (intrinsic spin-Hall effect) might apply to our system.