Topologically protected hybrid states in graphene–stanene–graphene heterojunctions

Abstract

A gapless conducting boundary state is one of the salient features of time-reversal-invariant topological insulators (TIs), which have attracted a lot of interest due to their fundamental importance and practical applications. Achieving robust non-trivial edge channels at the solid-state interface is a crucial step towards functional junction-based modern electronic devices. Here, we report a van der Waals heterostructure based graphene–stanene–graphene (C–Sn–C) quantum wall (QW), which shows a topologically protected hybrid state at the graphene–stanene interface. The inverted band ordering and metallic edge states confirm the non-trivial band topology with a non-trivial band gap of 0.15 eV, which is considerably higher than that of stanene. We find that the hybrid state in the QW provides topological protection in graphene. The high carrier mobility of graphene and the QSH state of stanene may coexist in the C–Sn–C system and that could pave the way to novel spin-based electronic devices.