Metal–insulator-like transition, superconducting dome and topological electronic structure in Ga-doped Re3Ge7

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 Re3Ge7, which undergoes a second-order metal–insulator-like transition at ~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 Re3Ge7−xGax. As a consequence, the phase transition is gradually suppressed and disappears above x = 0.2. At this x value, superconductivity emerges and Tc 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 Re3Ge7 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 Re3Ge7 provides a rare opportunity to study the interplay between superconductivity and competing electronic states in a topologically nontrivial system.