Pressure-induced electronic topological transition and superconductivity in topological insulator Bi2Te2.1Se0.9

TL;DR

This study demonstrates how applying pressure induces structural and electronic topological transitions in Bi2Te2.1Se0.9, leading to superconductivity and revealing the interplay between topological states and superconductivity.

Contribution

It provides the first detailed analysis of pressure-induced structural and electronic transitions promoting superconductivity in Bi2Te2.1Se0.9, a topological insulator.

Findings

Superconductivity appears at 2.4 GPa with Tc around 6.6 K.

Electronic topological transition occurs near 2.5 GPa, influencing superconductivity.

Multiple pressure-induced structural phases are identified up to 37 GPa.

Abstract

One approach to discovering topological superconductor is establishing superconductivity based on well-identified topological insulators. However, the coexistence of superconductivity and topological state is always arcane. In this paper, we report how pressure tunes the crystal structure, electronic structure, and superconductivity in topological insulator Bi2Te2.1Se0.9. The first pressure-induced structure transition start from 8.4 GPa, followed by the structure sequence of R-3m - C2/m - C2/c - Im-3m up to 37 GPa. Superconductivity starts to present at 2.4 GPa with the Tc around 6.6 K. Moreover, at around 2.5 GPa, the abnormal changes of c/a and the full width at half maximum (FWHM) of mode indicate the occurrence of electronic topological transition (ETT). These results suggest that ETT highly promotes the superconductivity in topological insulator Bi2Te2.1Se0.9 in the low-pressure rhombohedral phase. Our work clarifies the complex electronic structure in Bi2Te2.1Se0.9 and sheds light on the new candidate for superconductivity in topological insulators.