Nondissipative Spin Hall Effect via Quantized Edge Transport

TL;DR

This paper demonstrates that in a 2D honeycomb lattice system, the spin Hall conductance remains quantized and robust against disorder and Rashba coupling variations, linked to a topological invariant, revealing a nondissipative edge transport mechanism.

Contribution

It provides numerical evidence of quantized spin Hall conductance in a honeycomb lattice with intrinsic spin-orbit coupling, even with Rashba coupling and disorder, highlighting topological protection.

Findings

Quantized spin Hall conductance at zero Rashba coupling.

Robustness of conductance against disorder and Rashba coupling.

Quantized charge transport via topologically protected edge channels.

Abstract

The spin Hall effect in a two-dimensional electron system on honeycomb lattice with both intrinsic and Rashba spin-orbit couplings is studied numerically. Integer quantized spin Hall conductance is obtained at zero Rashba coupling limit when electron Fermi energy lies in the energy gap created by the intrinsic spin-orbit coupling, in agreement with recent theoretical prediction. While nonzero Rashba coupling destroys electron spin conservation, the spin Hall conductance is found to remain near the quantized value, being insensitive to disorder scattering, until the energy gap collapses with increasing the Rashba coupling. We further show that the charge transport through counterpropagating spin-polarized edge channels is well quantized, which is associated with a topological invariant of the system.