Topological surface states of Bi2Se3 with the coexistence of Se vacancies

TL;DR

This paper investigates how selenium vacancies affect the topological surface states of Bi2Se3, revealing significant modifications in band structure and surface state localization due to surface defects.

Contribution

It demonstrates the impact of Se vacancies on the surface band structure and provides simulated STM images to distinguish surface terminations.

Findings

Se vacancies cause topological surface states to sink below the first layer.

Surface defects significantly alter the band dispersion of topological states.

Simulated STM images can differentiate Se- and Bi-terminated surfaces.

Abstract

Although topological surface states are known to be robust against non-magnetic surface perturbations, their band dispersions and spatial distributions are still sensitive to the surface defects. Take Bi2Se3 as an example, we demonstrated that Se vacancies modifies the surface band structures considerably. When large numbers of Se vacancies exist on the surface, topological surface states may sink down from the first to second quintuple layer and get separated from the vacancies. We simulated STM images to distinguish the surfaces with Se- and Bi-terminations.