Spin polarization of the L-gap surface states on Au(111)

TL;DR

This paper theoretically investigates the spin polarization of surface states on Au(111), revealing large in-plane spin-orbit effects and a small out-of-plane component, with implications for photoemission spectroscopy analysis.

Contribution

It provides a detailed first-principles analysis of the spin polarization of Au(111) surface states, including the effects of surface corrugation and photoemission conditions.

Findings

Large in-plane ESP induced by spin-orbit coupling

Small out-of-plane ESP component due to surface corrugation

Guidelines for photoemission experiments to probe surface ESP

Abstract

The electron spin polarization (ESP) of the L-gap surface states on Au(111) is investigated theoretically by means of first-principles electronic-structure and photoemission calculations. The surface states show a large spin-orbit induced in-plane ESP which is perpendicular to the in-plane wavevector, in close analogy to a two-dimensional electron gas with Rashba spin-orbit interaction. The surface corrugation leads to a small ESP component normal to the surface, being not reported so far. The surface-states ESP can be probed qualitatively and quantitatively by spin- and angle-resolved photoelectron spectroscopy, provided that the initial-state ESP is retained in the photoemission process and not obscured by spin-orbit induced polarization effects. Relativistic photoemission calculations provide detailed information on what photoemission set-ups allow to conclude from the photoelectron ESP on that of the surface states.