Spin Hall effect in graphene due to random Rashba field

TL;DR

This paper theoretically demonstrates that random Rashba spin-orbit coupling in graphene can induce a nonzero spin Hall effect, with conductivity depending on relaxation rates, highlighting a novel mechanism for spin transport.

Contribution

It introduces a theoretical model showing how fluctuations in Rashba coupling generate spin Hall conductivity in graphene, a phenomenon not previously characterized.

Findings

Random Rashba fields induce spin Hall effect in graphene.

Spin Hall conductivity depends on momentum and spin-flip relaxation rates.

The effect is non-universal and varies with disorder strength.

Abstract

Spin Hall effect due to random Rashba spin-orbit coupling in the two-dimensional honeycomb lattice of carbon atoms (graphene) is considered theoretically. Using the Green function method and diagrammatic technique we show that fluctuations of the Rashba interaction around zero average value give rise to nonzero spin Hall conductivity. Generally, the conductivity is not universal, but depends on the ratio of the total momentum and spin-flip relaxation rates.