First-principles investigation of possible room-temperature topological insulators in monolayers

Abstract

A Quantum Spin Hall (QSH) insulator with a large bulk band gap and tunable topological properties is crucial for both fundamental research and practical application. Chemical function-alization has been proposed as an effective route to realize the QSH effect. Using the ABINIT package, we have investigated the properties of (1) TlP, the functionalized monolayers TlPX₂ (X = F, Cl, Br, I); (2) TlAs, the functionalized monolayers TlAsX₂ (X = F, Cl, Br, I), and (3) GaGeTe, InGeTe, and InSnTe systems. The topological nature is verified by the calculation of the Z₂ topo-logical invariant. We discovered TlPF₂, TlPCl₂, TlPBr₂, TlPI₂, TlAs, TlAsF₂, TlAsCl₂, TlAsBr₂, and TlAsI₂ were promising 2D TIs with bulk band gaps as large as 0.21 eV. Each monolayer was suitable for room-temperature application, and show great potential for their future applications in quantum computers, nanoelectronics, and spintronics.