Experimental observation of the spin-Hall effect in a two dimensional spin-orbit coupled semiconductor system

TL;DR

This paper reports the first experimental detection of the spin-Hall effect in a 2D hole system with Rashba spin-orbit coupling, demonstrating out-of-plane spin polarization induced by an electric field.

Contribution

It provides experimental evidence of the intrinsic spin-Hall effect in a 2D semiconductor with Rashba coupling, using a novel co-planar geometry for polarization detection.

Findings

Out-of-plane spin polarization depends on electric field sign

Weak disorder effects suggest intrinsic spin-Hall conductance

Experimental setup allows angle-resolved polarization detection

Abstract

We report the experimental observation of the spin-Hall effect in a two-dimensional (2D) hole system with Rashba spin-orbit coupling. The 2D hole layer is a part of a p-n junction light-emitting diode with a specially designed co-planar geometry which allows an angle-resolved polarization detection at opposite edges of the 2D hole system. In equilibrium the angular momenta of the Rashba split heavy hole states lie in the plane of the 2D layer. When an electric field is applied across the hole channel a non zero 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.