Pressure induced re-emergence of superconductivity in superconducting topological insulator Sr0.065Bi2Se3

TL;DR

This study demonstrates that applying pressure to Sr0.065Bi2Se3 suppresses initial superconductivity, but a new superconducting phase re-emerges at higher pressures due to structural phase transitions.

Contribution

It reveals pressure-induced re-emergence of superconductivity in Sr0.065Bi2Se3 linked to structural phase changes, expanding understanding of topological superconductor behavior under pressure.

Findings

Superconductivity is suppressed at low pressure.

A new superconducting phase appears above 6 GPa.

Structural transitions correlate with superconductivity re-emergence.

Abstract

The recent-discovered Sr$_x$Bi$_2$Se$_3$ superconductor provides an alternative and ideal material base for investigating possible topological superconductivity. Here, we report that in Sr$_{0.065}$Bi$_{2}$Se$_3$, the ambient superconducting phase is gradually depressed upon the application of external pressure. At high pressure, a second superconducting phase emerges at above 6 GPa, with a maximum $T_c$ value of $\sim$8.3 K. The joint investigations of the high-pressure synchrotron x-ray diffraction and electrical transport properties reveal that the re-emergence of superconductivity in Sr$_{0.065}$Bi$_{2}$Se$_3$ is closely related to the structural phase transition from ambient rhombohedral phase to high-pressure monoclinic phase around 6 GPa, and further to another high-pressure tetragonal phase above 25 GPa.