First Principles Calculations of the Topological Insulator Stanene on an Al₂O₃ Substrate

Topological insulators are a class of materials under continuing investigation due to their potential for hosting robust current-carrying surface or edge states. Stanene, the two-dimensional monolayer form of tin, has been predicted to be a 2D topological insulator due to its large spin-orbit interaction, but a clear experimental demonstration of this behavior has eluded observation. In part, this is because the choice of growth substrate has a major effect on the electronic and topological properties of stanene due to the imposition of both epitaxial strain and bonding interactions between the substrate and the stanene monolayer. We present first-principles density functional theory (DFT) calculations of monolayer stanene grown on the (0001) surface of alumina, Al₂O₃. We perform a detailed analysis of the binding energy and electronic structure of stanene on Al₂O₃, and compute the system’s Z₂ topological invariant. In addition, we describe other potential structures of tin on the alumina surface, and analyze their competition with monolayer stanene.