2D transport and screening in topological insulator surface states

TL;DR

This paper investigates how disorder affects the surface states of topological insulator Bi$_2$Se$_3$, focusing on charge puddles and their impact on electronic properties near charge neutrality.

Contribution

It introduces a detailed analysis of disorder effects on topological insulator surface states, emphasizing the role of band asymmetry in electronic behavior.

Findings

Charge puddles dominate near charge neutrality.

Band asymmetry significantly influences conductivity.

Puddle autocorrelation length is affected by disorder.

Abstract

We study disorder effects on the surface states of the topological insulator Bi$_2$Se$_3$ close to the topologically protected crossing point. Close to charge neutrality, local fluctuations in carrier density arising from the random charged disorder in the environment result in electron and hole puddles that dominate the electronic properties of these materials. By calculating the polarizability of the surface state using the random phase approximation, and determining the characteristics of puddles using the self-consistent approximation, we find that band asymmetry plays a crucial role in determining experimentally measured quantities including the conductivity and the puddle autocorrelation length.