Chemically-induced large-gap quantum anomalous Hall insulator states in III-Bi honeycombs

Abstract

The search for new novel materials has increased due to their interesting properties and promising applications. Quantum anomalous Hall (QAH) effect was recently realized in magnetic topological insulators (TIs) but only observable at extremely low temperatures. In this work, we predict large-gap QAH insulating phases in chemically functionalized III-Bi honeycombs using first-principles electronic structure calculations. QAH insulator phases were found in functionalized AlBi and TlBi, while QAH semimetals were identified in GaBi and InBi using electronic band calculation with exchange field and spin-orbit coupling. We further confirm QAH phase in these compounds by evaluating the Chern number (C) using maximally-localized Wannier functions. Most importantly, TlBi exhibits a robust with large-gap QAH insulator phases with band gap as large as 466 meV for one-sidedly functionalized and buckled honeycomb. Furthermore, the electronic band spectrum of functionalized TlBi nanoribbon with zigzag edge is shown to possess only one spin chiral edge band crossing the Fermi level within the band gap. With the recent progress of III-V materials, our results suggest that III-Bi honeycomb would provide a new platform for developing novel spintronics devices based on the QAH phase.