Interplay of Topological States on TI/TCI Interfaces

Based on first-principles calculations, we study electronic structure of interfaces between a [Formula: see text] topological insulator (TI) SnBi [Formula: see text] Te [Formula: see text] and a topological crystalline insulator (TCI) SnTe. We consider two interface models characterized by the different atomic structure on the contact of the SnTe(111) and SnBi [Formula: see text] Te [Formula: see text] (0001) slabs: the model when two materials are connected without intermixing (abrupt type of interface) and the interface model predicted to be realized at epitaxial immersion growth on topological insulator substrates (smooth interface). We find that a strong potential gradient at the abrupt interface leads to the redistribution of the topological states deeper from the interface plane which prevents the annihilation of the [Formula: see text] Dirac states, predicted earlier. In contrast, a smooth interface is characterized by minor charge transfer, which promotes the strong interplay between TI and TCI [Formula: see text] Dirac cones leading to their complete annihilation.The [Formula: see text] topologically protected Dirac state of SnTe(111) survives irrespective of the interface structure.