Landau quantization and the thickness limit of topological insulator thin films of Sb2Te3

TL;DR

This study experimentally observes Landau quantization in Sb2Te3 topological insulator thin films, revealing a thickness limit of four quintuple layers for maintaining 3D topological insulator properties and showing robustness against defects.

Contribution

It provides the first experimental evidence of Landau quantization in Sb2Te3 thin films and identifies the critical thickness limit for topological insulator behavior.

Findings

Landau quantization observed in Sb2Te3 films via STM

Robustness of surface states against intrinsic defects

Thickness limit of four quintuple layers for 3D topological insulator

Abstract

We report the experimental observation of Landau quantization of molecular beam epitaxy grown Sb2Te3 thin films by a low-temperature scanning tunneling microscope. Different from all the reported systems, the Landau quantization in Sb2Te3 topological insulator is not sensitive to the intrinsic substitutional defects in the films. As a result, a nearly perfect linear energy dispersion of surface states as 2D massless Dirac fermion system is achieved. We demonstrate that 4 quintuple layers are the thickness limit for Sb2Te3 thin film being a 3D topological insulator. The mechanism of the Landau level broadening is discussed in terms of enhanced quasiparticle lifetime.