Engineering Multiple Topological Phases in Nanoscale Van der Waals Heterostructures: Realisation of $\alpha$-Antimonene

TL;DR

This paper demonstrates the creation of nanoscale van der Waals heterostructures with multiple topological phases, including the first experimental realization of $eta$- and $ ext{alpha}$-antimonene, which are topologically non-trivial materials.

Contribution

It reports the first experimental synthesis of $ ext{alpha}$-antimonene and shows how to engineer multiple topological phases within a single heterostructure.

Findings

Successfully synthesized $ ext{alpha}$-antimonene.

Heterostructures exhibit multiple topological phases.

$ ext{alpha}$-antimonene is a topologically non-trivial quantum spin Hall insulator.

Abstract

Van der Waals heterostructures have recently been identified as providing many opportunities to create new two-dimensional materials, and in particular to produce materials with topologically interesting states. Here we show that it is possible to create such heterostructures with multiple topological phases in a single nanoscale island. We discuss their growth within the framework of diffusion-limited aggregation, the formation of moir\'e patterns due to the differing crystallographies of the materials comprising the heterostructure, and the potential to engineer both the electronic structure as well as local variations of topological order. In particular we show that it is possible to build islands which include both the hexagonal $\beta$- and rectangular $\alpha$-forms of antimonene, on top of the topological insulator $\alpha$-bismuthene. This is the first experimental realisation of $\alpha$-antimonene, and we show that it is a topologically non-trivial material in the quantum spin Hall class.