Designer quantum spin Hall phase transition in molecular graphene

TL;DR

This paper proposes a method to create a highly controllable two-dimensional topological insulator by growing designer honeycomb lattices on substrates with strong spin-orbit interactions, overcoming graphene's weak spin-orbit coupling.

Contribution

It introduces a novel approach to realize topological insulators using engineered lattices on suitable substrates with strong spin-orbit coupling.

Findings

Estimated substrate parameters for topological phase realization

Identified candidate substrates for experimental implementation

Proposed a scalable method for designer topological insulators

Abstract

Graphene was the first material predicted to be a time-reversal-invariant topological insulator; however, the insulating gap is immeasurably small owing to the weakness of spin-orbit interactions in graphene. A recent experiment [1] demonstrated that designer honeycomb lattices with graphene-like "Dirac" band structures can be engineered by depositing a regular array of carbon monoxide atoms on a metallic substrate. Here, we argue that by growing such designer lattices on metals or semiconductors with strong spin-orbit interactions, one can realize an analog of graphene with strong intrinsic spin-orbit coupling, and hence a highly controllable two-dimensional topological insulator. We estimate the range of substrate parameters for which the topological phase is achievable, and consider the experimental feasibility of some candidate substrates.