We show that two different superconducting phases exist at high pressures in the optimized tetradymite topological insulators Bi2Te2Se (BTS) and Bi1.1Sb0.9Te2S (BSTS). The superconducting phases emerge at structural phase transitions, the first at 8.4 GPa for BTS and 12.4 GPa for BSTS, and the second at 13.6 GPa for BTS and 20.4 GPa, for BSTS. Electronic structure calculations show that these phases do not have topological character. Comparison of our results with prior work on Bi2Se3, Bi2Te3 and (Bi,Sb)2(Se,Te)3 allows us to uncover a universal phase diagram for pressure-induced superconductivity in tetradymites, providing a basis for understanding the relationships between topological behavior, crystal structure, and superconductivity for these materials.
@article{arxiv.1808.10295,
title = {Universal superconductivity phase diagram for pressurized tetradymite topological insulators},
author = {Shu Cai and S. K. Kushwaha and Jing Guo and Vladimir A. Sidorov and Congcong Le and Yazhou Zhou and Honghong Wang and Gongchang Lin and Xiaodong Li and Yanchuan Li and Ke Yang and Aiguo Li and Qi Wu and Jiangping Hu and Robert J Cava and Liling Sun},
journal= {arXiv preprint arXiv:1808.10295},
year = {2018}
}