Pressured-induced superconductivity extending across the topological phase transition in thallium-based topological materials TlBi(S1-xSex)2

TL;DR

This study demonstrates pressure-induced superconductivity in thallium-based topological materials, revealing topological surface states across a phase transition, and suggests potential for realizing topological superconductivity.

Contribution

It reports the discovery of pressure-induced superconductivity across a topological phase transition in TlBi(S1-xSex)2 compounds, combining experimental and theoretical insights.

Findings

Superconductivity observed up to 8.1 K under 60 GPa pressure.

Topological surface states persist in superconducting phases.

Superconductivity spans the transition from insulator to topological insulator.

Abstract

The coexistence of superconductivity and topology holds the potential to realize exotic quantum states of matter. Here we report that superconductivity induced by high pressure in three thallium-based materials, covering the phase transition from a normal insulator (TlBiS2) to a topological insulator (TlBiSe2) through a Dirac semimetal (TlBiSeS). By increasing the pressure up to 60 GPa, we observe superconductivity phase diagrams with maximal Tc values at 6.0-8.1 K. Our density-functional theory calculations reveal topological surface states in superconductivity phases for all three compounds. Our study paves the path to explore topological superconductivity and topological phase transitions.