Discovery of Room-Temperature Topological Insulators in Functionalized Group VA-VA Binary Monolayers: A First-Principles Investigation.

Topological insulators and semimetals are necessary to realize quantum computing and spintronics. We use first-principles calculations to investigate the atomic structure, electronic band structure, and Z2 invariants of four sets of pure and functionalized buckled hexagonal monolayers that are promising candidates for topological nature: BiAs, AsP, SbAs, BiSb, and functionalized monolayers BiAsX2, AsPX2, SbAsX2, and BiSbX2 (X = H, O, S). Our results show that BiAsO2, BiAsS2, AsPO2, SbAsO2, SbAsS2, BiSbH2, BiSbO2, and BiSbS2 are topological insulators with small SOC-induced band gaps ranging from 0.05 to 0.37 eV. Further, we propose AsPS2 to be a topological semiconductor. Topological insulators stand on the boundary of induction and conductance and are crucial in realizing quantum computers. The room-temperature topological insulators predicted here will have promising impacts in quantum computing, nanoelectronics, and spintronics.