Quantum spin Hall insulator in halogenated arsenene films with sizable energy gaps

Based on first-principles calculations, the electronic and topological properties of halogenated (F-, Cl-, Br- and I-) arsenene are investigated in detail. It is found that the halogenated arsenene sheets show Dirac type characteristic in the absence of spin-orbital coupling (SOC), whereas energy gap will be induced by SOC with the values ranging from 0.194 eV for F-arsenene to 0.255 eV for I-arsenene. Noticeably, these four newly proposed two-dimensional (2D) systems are verified to be quantum spin Hall (QSH) insulators by calculating the edge states with obvious linear cross inside bulk energy gap. It should be pointed out that the large energy gap in these 2D materials consisted of commonly used element is quite promising for practical applications of QSH insulators at room temperature.