Dirac quantum well engineering on the surface of topological insulator

TL;DR

This paper explores the electronic states in a Dirac quantum well formed by a thin topological insulator layer between trivial insulators, revealing hybridization effects and differences between chiral and massive interface states.

Contribution

It introduces a model of a Dirac quantum well with smooth interfaces, analyzing hybridization effects on chiral and Volkov-Pankratov states in topological insulator heterostructures.

Findings

Strong hybridization of massive Volkov-Pankratov states due to quantum tunneling.

Weak effect on chiral interface states despite hybridization.

Distinct behaviors of interface states depending on well width and interface size.

Abstract

We investigate a quantum well that consists of a thin topological insulator sandwiched between two trivial insulators. More specifically, we consider smooth interfaces between these different types of materials such that the interfaces host not only the chiral interface states, whose existence is dictated by the bulk-edge correspondence, but also massive Volkov-Pankratov states. We investigate possible hybridization between these interface states as a function of the width of the topological material and of the characteristic interface size. Most saliently, we find a strong qualitative difference between an extremely weak effect on the chiral interface states and a more common hybridization of the massive Volkov-Pankratov states that can be easily understood in terms of quantum tunneling in the framework of the model of a (Dirac) quantum well we introduce here.