Nonequilibrium spin transport on Au(111) surfaces

TL;DR

This paper models Au(111) surface states with Rashba spin splitting using a tight-binding approach and predicts nonequilibrium spin transport phenomena such as spin-Hall effect, spin polarization, and Rashba precession, urging experimental verification.

Contribution

It introduces a tight-binding model for Au(111) surface states and predicts spin transport effects not yet observed in metallic surfaces.

Findings

Strong spin density on Au(111) surface

Intrinsic spin-Hall effect predicted

Current-induced spin polarization and Rashba precession demonstrated

Abstract

The well-known experimentally observed \textit{sp}-derived Au(111) Shockley surface states with Rashba spin splitting are perfectly fit by an effective tight-binding model, considering a two-dimensional hexagonal lattice with $p_{z}$-orbital and nearest neighbor hopping only. The extracted realistic band parameters are then imported to perform the Landauer-Keldysh formalism to calculate nonequilibrium spin transport in a two-terminal setup sandwiching a Au(111) surface channel. Obtained results show strong spin density on the Au(111) surface and demonstrate (i) intrinsic spin-Hall effect, (ii) current-induced spin polarization, and (iii) Rashba spin precession, all of which have been experimentally observed in semiconductor heterostructures, but not in metallic surface states. We therefore urge experiments in the latter for these spin phenomena.