Topological States at Interfaces and in Heterostructures*

Engineering topological insulator (TI) devices involves making heterostructures which combine these materials with other compounds. For a model Hamiltonian, it was shown [1] that properties of the topological interface states may differ from those of the surface states. Motivated by this observation we use a combination of ab initio and model calculations to investigate the consequences of interface potentials breaking spatial symmetries (with and without time reversal symmetry breaking) on the spectral and spin properties of the interface states. We use first principles density functional theory calculations to investigate the topological states at the boundaries between Bi₂Se₃ and binary semiconductors and magnetic insulators, obtain the form of the spin-momentum locking and anisotropy of energy dispersion, and compare these features with the outcomes of model analytical calculations. We also make connections with recent experiments on topological heterostructures, and discuss the importance of our results for tuning topological materials for potential device applications.
[1] M. M. Asmar, D. E. Sheehy, and I. Vekhter, PRB 95, 241115(R) (2017)