Prediction of silicon-based room temperature quantum spin Hall insulator via orbital mixing

The search for realistic materials capable of supporting the room temperature quantum spin Hall (QSH) effect remains a challenge, especially when compatibility with the current electronics industry is required. We report a theoretical prediction to identify halogenated silicon films as excellent candidates, which demonstrate high stability, flexibility, and tunable spin-orbit coupling (SOC) gaps up to similar to 0.5 eV under minimal strain below 3%. The extraordinary SOC strength is mainly contributed by the p-orbital of heavy halogen atoms hybridized with the p(x,y)-orbitals of Si scaffold, and thus can be easily manipulated by strain (being similar to 100 times more effective than in silicene) or substrate. Not only the instability problem of silicene for real applications is solved, but also it provides a new strategy to drastically enhance SOC of light-element scaffolds by orbital hybridization. The silicon-based QSH insulator is most promising for developing next-generation, low-power consumption nanoelectronics and spintronics at ambient conditions. Copyright (C) EPLA, 2016