Non-trivial Surface-band Dispersion on Bi(111)

TL;DR

This study uses angle-resolved photoelectron spectroscopy to reveal non-trivial topological edge states on the Bi(111) surface, indicating a topologically non-trivial phase in bulk bismuth.

Contribution

It demonstrates the existence of non-trivial surface states on Bi(111) and explains their origin through band structure analysis without requiring band inversion at the L point.

Findings

Surface states disperse from valence to conduction bands along ar{ ext{M}} direction

Non-trivial topological order confirmed in Bi(111) surface

Band structure can be explained by modified tight-binding parameters

Abstract

We performed angle-resolved photoelectron spectroscopy of the Bi(111) surface to demonstrate that this surface support edge states of non-trivial topology. Along the $\bar{\Gamma}\bar{M}$-direction of the surface Brillouin zone, a surface-state band disperses from the projected bulk valence bands at $\bar{\Gamma}$ to the conduction bands at $\bar{M}$ continuously, indicating the non-trivial topological order of three-dimensional Bi bands. We ascribe this finding to the absence of band inversion at the $L$ point of the bulk Bi Brillouin zone. According to our analysis, a modification of tight-binding parameters can account for the non-trivial band structure of Bi without any other significant change on other physical properties.