Search for Topological Insulators in Ternary Chalcogenides

A topological insulator (TI) is a novel quantum state, which is a bulk insulator but has gapless surface states. Recently, binary chalcogenides, Bi2Te3, Bi2Se3 and Sb2Te3 have been theoretically predicted and experimentally observed to be a family of TIs [1]. In this talk, we extend our search of TIs to ternary chalcogenides by replacing some of Bi or Sb atoms by other atoms, such as thallium and rare earth atoms. It is found that for thallium-based materials [2], only TlSbS2 is trivial and all the others are TIs, while for rare earth-based materials[3], LaBiTe3 is a TI and the others are trivial. The search in ternary chalcogenides not only bring new members of TIs in the family of chalcogenides but also may provide candidates for other new topological states such as topological superconductor, quantum anomalous Hall insulator, axionic insulator and topological Kondo insulator. \\[4pt] Reference:\\[0pt] [1] Topological insulators in Bi2Se3, Bi2Te3 and Sb2Te3 with a single Dirac cone on the surface, Haijun Zhang, Chao-Xing Liu, Xiao-Liang Qi, Xi Dai, Zhong Fang and Shou-ChengZhang, Nature Physics 5, 438 - 442 (2009).\\[0pt] [2] Theoretical prediction of topological insulators in thallium-based III-V-VI2 ternary chalcogenides, Binghai Yan, Chao-Xing Liu, Hai-Jun Zhang, ChiYung Yam, Xiao-Liang Qi, Thomas Frauenheim and Shou-Cheng Zhang, Europhysics Letters, 90, 37002 (2010).\\[0pt] [3] Theoretical prediction of topological insulator in ternary rare earth chalcogenides, Binghai Yan, Hai-Jun Zhang, Chao-Xing Liu, Xiao-Liang Qi, Thomas Frauenheim, Shou-Cheng Zhang, Phys. Rev. B 82, 161108(R) (2010).