Tuning the vertical location of helical surface states in topological insulator heterostructures via dual-proximity effects

TL;DR

This paper demonstrates how the vertical position of topological surface states in topological insulator heterostructures can be precisely tuned using dual-proximity effects, enabling control over quantum phase transitions.

Contribution

It introduces a first-principles method to accurately manipulate the vertical location of TSS in TI heterostructures through dual-proximity effects with conventional insulators.

Findings

TSS can be moved to the top of the CI layer or remain at the interface.

TSS can be pushed deeper into the TI substrate.

Material-specific properties of the CI influence TSS behavior.

Abstract

In integrating topological insulators (TIs) with conventional materials, one crucial issue is how the topological surface states (TSS) will behave in such heterostructures. We use first-principles approaches to establish accurate tunability of the vertical location of the TSS via intriguing dual-proximity effects. By depositing a conventional insulator (CI) overlayer onto a TI substrate (Bi2Se3 or Bi2Te3), we demonstrate that, the TSS can float to the top of the CI film, or stay put at the CI/TI interface, or be pushed down deeper into the otherwise structurally homogeneous TI substrate. These contrasting behaviors imply a rich variety of possible quantum phase transitions in the hybrid systems, dictated by key material-specific properties of the CI. These discoveries lay the foundation for accurate manipulation of the real space properties of TSS in TI heterostructures of diverse technological significance.