An increase in $T_c$ under hydrostatic pressure in the superconducting doped topological insulator Nb$_{0.25}$Bi$_2$Se$_3$

TL;DR

This study reveals that applying hydrostatic pressure up to 0.6 GPa increases the superconducting transition temperature in Nb$_{0.25}$Bi$_2$Se$_3$, contrary to similar materials, aligning with theoretical predictions for nematic multicomponent states.

Contribution

It demonstrates an unexpected positive pressure effect on $T_c$ in doped Bi$_2$Se$_3$, supporting recent theoretical models of nematic superconductivity.

Findings

Pressure up to 0.6 GPa increases $T_c$ in Nb$_{0.25}$Bi$_2$Se$_3$

Contrasts with suppression of $T_c$ in related compounds

Supports theory of pressure-induced enhancement in nematic states

Abstract

We report an unexpected positive hydrostatic pressure derivative of the superconducting transition temperature in the doped topological insulator \NBS via $dc$ SQUID magnetometry in pressures up to 0.6 GPa. This result is contrary to reports on the homologues \CBS and \SBS where smooth suppression of $T_c$ is observed. Our results are consistent with recent Ginzburg-Landau theory predictions of a pressure-induced enhancement of $T_c$ in the nematic multicomponent $E_u$ state proposed to explain observations of rotational symmetry breaking in doped Bi$_2$Se$_3$ superconductors.