Mesoscopic Spin-Hall Effect in 2D electron systems with smooth boundaries

TL;DR

This paper investigates the mesoscopic spin-Hall effect in ballistic 2D electron gases with Rashba spin-orbit coupling, revealing complex spin density features near smooth boundaries influenced by classical trajectories and quantum spin dynamics.

Contribution

It introduces a detailed analysis of spin density features near smooth edges, highlighting the interplay of semiclassical motion and quantum spin effects in the spin-Hall effect.

Findings

Strong spin density peaks near vanishing Fermi velocity points

Extended regions of negative and positive spin density along the edge

Enhanced features with shallower boundary potentials

Abstract

Spin-Hall effect in ballistic 2D electron gas with Rashba-type spin-orbit coupling and smooth edge confinement is studied. We predict that the interplay of semiclassical electron motion and quantum dynamics of spins leads to several distinct features in spin density along the edge that originate from accumulation of turning points from many classical trajectories. Strong peak is found near a point of the vanishing of electron Fermi velocity in the lower spin-split subband. It is followed by a strip of negative spin density that extends until the crossing of the local Fermi energy with the degeneracy point where the two spin subbands intersect. Beyond this crossing there is a wide region of a smooth positive spin density. The total amount of spin accumulated in each of these features exceeds greatly the net spin across the entire edge. The features become more pronounced for shallower boundary potentials, controlled by gating in typical experimental setups.