Spin-flip transitions induced by time-dependent electric fields in surfaces with strong spin-orbit interaction

TL;DR

This paper theoretically investigates how time-dependent electric fields induce spin-flip transitions on Pb/Ge(111) surfaces with strong spin-orbit coupling, revealing significant light absorption and potential for optical spin control.

Contribution

It demonstrates that electron spin-flip transitions significantly enhance light absorption and are localized in hot spots, providing new insights into spin-orbit phenomena on surfaces.

Findings

Spin-flip transitions account for up to 6% of light absorption.

Enhanced absorption is an order of magnitude greater than in Rashba systems.

Spin-flip hot spots are associated with 90-degree spin rotations.

Abstract

We present a comprehensive theoretical investigation of the light absorption rate at the Pb/Ge(111) surface with strong spin-orbit coupling. Our calculations show that electron spin-flip transitions cause as much as 6% of the total light absorption, representing one order of magnitude enhancement over Rashba-like systems. Thus, it is demonstrated that a substantial part of the light irradiating this nominally non-magnetic surface is attenuated in spin flip processes. Remarkably, the spin-flip transition probability is structured in well defined hot spots within the Brillouin zone where the electron spin experiences a sudden 90 degree rotation. This mechanism offers the possibility of an experimental approach to the spin-orbit phenomena by optical means.