Direct Observation of Interband Spin-Orbit Coupling in a Two-Dimensional Electron System

TL;DR

This study directly observes interband spin-orbit coupling in a 2D electron system, revealing significant deviations from Rashba behavior and demonstrating tunability via film thickness, advancing understanding of spin interactions in surface states.

Contribution

It provides the first direct experimental evidence of interband spin-orbit coupling in 2D surface states and shows how it can be controlled by film thickness.

Findings

Interband spin-orbit coupling significantly alters electronic dispersion.

The effect is tunable by changing the film thickness.

Deviations from the Rashba model are observed.

Abstract

We report the direct observation of interband spin-orbit (SO) coupling in a two-dimensional (2D) surface electron system, in addition to the anticipated Rashba spin splitting. Using angle-resolved photoemission experiments and first-principles calculations on Bi/Ag/Au heterostructures we show that the effect strongly modifies the dispersion as well as the orbital and spin character of the 2D electronic states, thus giving rise to considerable deviations from the Rashba model. The strength of the interband SO coupling is tuned by the thickness of the thin film structures.