A band structure scenario for the giant spin-orbit splitting observed at the Bi/Si(111) interface

TL;DR

This paper investigates the giant spin-orbit splitting at the Bi/Si(111) interface, revealing a new mechanism based on the underlying band structure through ARPES and tight-binding models.

Contribution

It introduces a novel explanation for the giant spin-orbit splitting at the Bi/Si(111) interface, emphasizing the role of the underlying band structure.

Findings

Identification of a complex hybrid interface band topology

Discovery of a new mechanism for spin-orbit splitting

Potential applicability to other trimer-structured interfaces

Abstract

The Bi/Si(111) (sqrt{3} x sqrt{3})R30 trimer phase offers a prime example of a giant spin-orbit splitting of the electronic states at the interface with a semiconducting substrate. We have performed a detailed angle-resolved photoemission (ARPES) study to clarify the complex topology of the hybrid interface bands. The analysis of the ARPES data, guided by a model tight-binding calculation, reveals a previously unexplored mechanism at the origin of the giant spin-orbit splitting, which relies primarily on the underlying band structure. We anticipate that other similar interfaces characterized by trimer structures could also exhibit a large effect.