The Realization of Topological Transition in Inse Monolayer with Decorated Oxygen Atoms Acting as Orbital Filter

Abstract

The successful fabrication of InSe films may lead to the next revolution of electronic industry. By first-principles method, the geometric and band structures of various configurations of oxygenated InSe (In8Se8OX) films are studied. When x<4, the systems are normal band insulator (NI), while the configurations turn to be topological insulators (TIs) when x≥4. The time-reversal protected topological characteristics could be speculated by s–pxy band inversion. This is confirmed by helical edge states. Oxygen atoms (O) act as orbital filters in realization of topological nontrivial properties. When an O atom is added on Se, they interact with each other because the Se atoms in the InSe surface are exposed. The orbits filer effect may remove the dangling pz orbits of Se, while px and py orbits remain active near Fermi energy. When enough O atoms added, the effect can trigger In8Se8OX to be a nontrivial phase. So, we provide a simple rule for InSe films to realize topological properties by adding certain numbers of O atoms. This would be a realizable way to design topological devices based on InSe film in experiments.

Keywords: InSe, Topological Insulator, orbits filter