Robustness of topologically protected surface states in layering of Bi2Te3 thin films

TL;DR

This study uses density-functional theory to examine the surface states of Bi2Te3 thin films, demonstrating their topological robustness across various thicknesses and confirming experimental observations.

Contribution

It introduces a new method to identify surface states in thin film topological insulators and confirms the persistence of topological surface states in Bi2Te3 films of multiple layers.

Findings

Surface states remain topologically robust regardless of film thickness.

Films with three or more quintuple layers exhibit protected surface states.

Results align with recent experimental findings.

Abstract

Bulk Bi2Te3 is known to be a topological insulator. We investigate surface states of Bi2Te3(111) thin films using density-functional theory including spin-orbit coupling. We construct a method to unambiguously identify surface states of thin film topological insulators. Applying this method for one to six quintuple layers of Bi2Te3, we find that the topological nature of the surface states remains robust with the film thickness and that the films of three or more quintuple layers have topologically non-trivial or protected surface states, in agreement with recent experiments.