Uniaxial Strain Induced Topological Phase Transition in Bismuth-Tellurohalide-Graphene Heterostructures

We explore the electronic structure and topological phase diagram of heterostructures formed of graphene and ternary bismuth tellurohalide layers. We show that mechanical strain inherently present in fabricated samples could induce a topological phase transition in single-sided heterostructures, turning the sample into a novel experimental realisation of a time reversal invariant topological insulator. We construct an effective tight binding description for low energy excitations and fit the models parameters to ab initio band structures. We propose a simple approach for predicting phase boundaries as a function of mechanical distortions and hence gain a deeper understanding on how the topological phase in the considered system may be engineered.