Spin Hall effect and Berry phase in two dimensional electron gas

TL;DR

This paper explores the spin Hall effect in a high mobility 2D electron gas with Rashba and Dresselhaus spin-orbit couplings, revealing how spin currents are generated and controlled, and linking conductance to Berry phase.

Contribution

It demonstrates the independence of spin Hall conductance from coupling strength and its dependence on the ratio of Rashba to Dresselhaus couplings, with controllable spin current direction.

Findings

Spin current is generated perpendicular to electric field.

Spin Hall conductance is independent of coupling strength.

Spin conductance sign depends on the ratio of Rashba and Dresselhaus couplings.

Abstract

The spin Hall effect is investigated in a high mobility two dimensional electron system with the spin-orbital coupling of both the Rashba and the Dresselhaus types. A spin current perpendicular to the electric field is generated by either the Rashba or the Dresselhaus coupling. The spin Hall conductance is independent of the stength of the coupling, but its sign is determined by the relative ratio of the two couplings. The direction of spin current is controllable by tuning the magnitude of the surface electric field perpendicular to the two dimensional plane via adjusting the Rashba coupling. It is observed that the spin Hall conductance has a close relation to the Berry phase of conduction electrons.