New families of quantum spin Hall insulators with rashba effect in functionalized InBi monolayers

Abstract

Because quantum spin Hall (QSH) insulators with dissipative electron transport properties have broad application prospect in the field of quantum devices, QSH insulators have aroused great research enthusiasm and many ideal QSH insulators are predicted successfully. Based on density functional calculations, we predict that new families of functionalized InBi monolayers, H–InBi-X (X = F, Cl, Br, I), to be QSH insulators. We find that the pristine InBi monolayer that is simultaneously hydrogenated and halogenated has a maximum band gap of 0.49 eV while preserving the untrivial topological properties, which is large enough for room-temperature applications. Because of the absence of inversion symmetry, the Rashba SOC effect occurs in the band structure and the SOC not only opens the bandgaps but also leads to the band inversion. In addition, the topological properties of these monolayers can survive a wide range of external strain from −6% to 6%. Our findings enrich the inversion-asymmetry topological materials and provide a reliable reference for designing QSH insulators at room temperature.