Universal superconductivity phase diagram for pressurized tetradymite topological insulators

TL;DR

This study reveals a universal pressure-induced superconductivity phase diagram in tetradymite topological insulators, showing two distinct superconducting phases associated with structural transitions, and clarifies their electronic topological properties.

Contribution

It uncovers a universal phase diagram for superconductivity in tetradymite topological insulators under pressure, linking structural transitions to superconducting phases and their topological characteristics.

Findings

Two superconducting phases at specific pressures in BTS and BSTS

Superconducting phases occur at structural phase transitions

These phases lack topological character

Abstract

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.