Spatial Distribution of Topological Surface State Electrons in Bi$_{2}$Se$_{3}$ Probed by Na$^{+}$ Low Energy Ion Scattering

TL;DR

This study uses Na$^{+}$ low energy ion scattering to experimentally map the spatial distribution of topological surface state electrons in Bi$_{2}$Se$_{3}$, revealing their positioning between atomic layers.

Contribution

It provides direct experimental evidence of the spatial distribution of TSS electrons in Bi$_{2}$Se$_{3}$ using ion scattering techniques.

Findings

Na$^{+}$ neutralization varies between Se and Bi surfaces

TSS electrons are mainly located between the first and second atomic layers

Ion scattering reveals the spatial charge redistribution in TSS

Abstract

Bi$_{2}$Se$_{3}$ is a topological insulator whose unique properties result from topological surface states (TSS) in the band gap. Low energy ion scattering can determine the properties of the outermost few atomic layers of a solid. The deposition of Cs helps to reveal that the neutralization of Na$^{+}$ is larger when scattered from surface Se than from Bi. This is caused by the spatial redistribution of the conductive charges in the TSS, which are primarily positioned between the first and second atomic layers. This provides direct experimental evidence of the spatial distribution of the TSS electrons.