Topological Phase Transitions in the Graphene/Bismuthene Heterostructure

This work investigates the topological properties and the effect of biaxial strain on the Graphene/Bismuthene heterostructure (HvdW G/B) in two different stackings, using first-principles calculations with the Quantum Espresso code. The electronic structures were analyzed, revealing the influence of spin-orbit coupling evidenced by anti-crossing points, band inversion, and Rashba-type splittings. Based on the electronic results, the Z2 invariant was calculated using the Z2Pack program, identifying a topological phase transition when switching between stackings. This suggests that it is possible to modify the topological properties by displacing one layer relative to the other. Furthermore, when biaxial strain is applied, interesting changes in the electronic and topological properties were observed. For one stacking, biaxial strain induces a phase transition at a deformation between 4% and 6%, turning the material from a trivial to a topological one. These findings show that mechanical strain is an effective tool to control topological properties, opening new possibilities for the design of electronic devices based on topological phases.