Unconventional Fermi surface spin textures in the Bi_xPb_{1-x}/Ag(111) surface alloy

TL;DR

This study investigates how alloy composition affects the spin textures of surface states in Bi_xPb_{1-x}/Ag(111), revealing a topological transition with unconventional spin arrangements that influence spin transport.

Contribution

It demonstrates the tunability of Fermi and Rashba energies and uncovers unconventional spin textures linked to a topological transition in the alloy surface states.

Findings

Unconventional spin textures observed at x=0.5

Surface states remain fully spin polarized after alloying

Spin polarization vectors are tangential to energy contours

Abstract

The Fermi and Rashba energies of surface states in the Bi_xPb_{1-x}/Ag(111) alloy can be tuned simultaneously by changing the composition parameter x. We report on unconventional Fermi surface spin textures observed by spin and angle-resolved photoemission spectroscopy {that are correlated with a topological transition of the Fermi surface occurring at x=0.5. We show that the surface states remain fully spin polarized upon alloying and that the spin polarization vectors are approximately tangential to the constant energy contours. We discuss the implications of the topological transition for the transport of spin.