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

¹ Beijing National Lab for Condensed Matter Physics & Institute of Physics, Chinese Academy of Sciences Beijing 100190, China
² Department of Physics, Tsinghua University - Beijing 100084, China
³ Collaborative Innovation Center of Quantum Matter - Beijing 100190, China

^(a) Present address: Institute of Physics, Chinese Academy of Sciences - P.O. Box 603, Beijing 100190, China; smeng@iphy.ac.cn

Received: 3 November 2015
Accepted: 29 March 2016

Abstract

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 ∼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 ∼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.