Living on the edge: Topology, electrostatics and disorder

TL;DR

This paper explores the coexistence of massless and massive topological edge states at material interfaces, using a modified Bernevig-Hughes-Zhang model to identify conditions and propose experiments for their detection and control.

Contribution

It introduces a minimal model incorporating electrostatic effects to predict and analyze the coexistence of different topological edge states, suggesting new experimental avenues.

Findings

Coexistence of massless and massive edge states identified

Parameter sets determining edge state characteristics found

Proposals for experimental detection and tuning provided

Abstract

We address the co-existence of massless and massive topological edge states at the interface between two materials with different topological phases. We modify the well known Bernevig-Hughes-Zhang model to introduce a smooth function describing the band inversion and the band bending due to electrostatic effects between the bulk of the quantum well and the vacuum. Within this minimal model we identify distinct parameter sets that can lead to the co-existence of the two types of edge states, and that determine their number and characteristics. We propose several experimental setups that could demonstrate their presence in two-dimensional topological systems, as well as ways to regulate or tune the contribution of the massive edge states to the conductance of associated electronic devices. Our results suggest that such states may also be present in novel two-dimensional Van der Waals topological materials.