The Structural Influence on the Rashba-type Spin-Splitting in Surface Alloys

TL;DR

This study investigates how structural asymmetry, specifically outward relaxation of atoms, influences the Rashba-type spin-splitting in surface alloys like Bi/Ag(111), Pb/Ag(111), and Sb/Ag(111), using LEED measurements.

Contribution

It provides experimental quantification of atomic relaxation and links structural features to spin-splitting mechanisms in surface alloys.

Findings

Outward relaxation significantly affects spin-splitting magnitude.

Structural asymmetry influences potential landscape and orbital character.

Different stacking orders in Sb/Ag(111) alloys are reproducibly formed.

Abstract

The Bi/Ag(111), Pb/Ag(111), and Sb/Ag(111) surface alloys exhibit a two-dimensional band structure with a strongly enhanced Rashba-type spin-splitting, which is in part attributed to the structural asymmetry resulting from an outward relaxation of the alloy atoms. In order to gain further insight into the spin-splitting mechanism, we have experimentally determined the outward relaxation of the alloy atoms in these surface alloys using quantitative low-energy electron diffraction (LEED). The structure plays an important role in the size of the spinsplitting as it dictates the potential landscape, the symmetry as well as the orbital character. Furthermore, we discuss the band ordering of the Pb/Ag(111) surface alloy as well as the reproducible formation of Sb/Ag(111) surface alloys with unfaulted (face-centered cubic) and faulted (hexagonally close-packed) toplayer stacking.