Spin-flip transitions and departure from the Rashba model in the Au(111) surface

TL;DR

This paper investigates spin-flip excitations on Au(111) surfaces, revealing significant deviations from the Rashba model in angular modulation and absorption rates, highlighting the need for more comprehensive models.

Contribution

The study provides a detailed analysis of spin-flip excitations incorporating full spinor structures and Wannier-based calculations, showing deviations from the Rashba model in dynamical properties.

Findings

Spin-flip excitations show important angular modulation absent in Rashba model.

Maximum spin-flip absorption rate is about twice the Rashba prediction.

Rashba model accurately describes spectrum and spin polarization but not dynamical properties.

Abstract

We present a detailed analysis of the spin-flip excitations induced by a periodic time-dependent electric field in the Rashba prototype Au(111) noble metal surface. Our calculations incorporate the full spinor structure of the spin-polarized surface states and employ a Wannier-based scheme for the spin-flip matrix elements. We find that the spin-flip excitations associated with the surface states exhibit an important angular modulation which is completely absent in the standard Rashba model \cite{rashba}. Furthermore, we demonstrate that the maximum of the calculated spin-flip absorption rate is about twice the model prediction. These results show that although the Rashba model accurately describes the spectrum and spin polarization, it does not fully account for the dynamical properties of the surface states.