Metal-insulator-like transition, superconducting dome and topological electronic structure in Ga-doped Re$_{3}$Ge$_{7}$

TL;DR

This study reports the discovery of superconductivity in Ga-doped Re3Ge7, a topological material with a metal-insulator-like transition, revealing the interplay between topological electronic structure and superconductivity.

Contribution

It demonstrates that Ga doping induces superconductivity in Re3Ge7 and preserves its nontrivial band topology, providing new insights into topological superconductors.

Findings

Superconductivity appears at x=0.2 with a maximum Tc of 3.37 K at x=0.25.

Ga doping suppresses the metal-insulator-like transition in Re3Ge7.

The nontrivial band topology remains after doping, as shown by first-principles calculations.

Abstract

Superconductivity frequently appears by doping compounds that show a collective phase transition. So far, however, this has not been observed in topological materials. Here we report the discovery of superconductivity induced by Ga doping in orthorhombic Re$_{3}$Ge$_{7}$, which undergoes a second-order metal-insulator-like transition at $\sim$58 K and is predicted to have a nontrivial band topology. It is found that the substitution of Ga for Ge leads to hole doping in Re$_{3}$Ge$_{7-x}$Ga$_{x}$. As a consequence, the phase transition is gradually suppressed and disappears above $x$ = 0.2. At this $x$ value, superconductivity emerges and $T_{\rm c}$ exhibits a dome-like doping dependence with a maximum value of 3.37 K at $x$ = 0.25. First-principles calculations suggest that the phase transition in Re$_{3}$Ge$_{7}$ is associated with an electronic instability driven by Fermi surface nesting and the nontrival band topology is preserved after Ga doping. Our results indicate that Ga-doped Re$_{3}$Ge$_{7}$ provides a rare opportunity to study the interplay between superconductivity and competing electronic states in a topologically nontrivial system.