Anomalous metallic phase and reduced critical current in superconducting nanowires due to inverse proximity effect

Abstract

Superconductor-to-metal transitions (SMTs) are key probes of mesoscopic superconductivity, but their interpretation can be complicated by device geometry and measurement conditions. Here, we study epitaxial InAs-Al nanowires and show that metallic contacts induce an inverse proximity effect (IPE), creating weak spots in the superconductor that strongly suppress the critical current and give rise to an anomalous metallic phase. Using transport measurements supported by Usadel theory, we demonstrate that this phase originates from the contact-induced weakening of superconductivity together with Joule heating, rather than intrinsic material properties. Our findings reveal an overlooked observer effect in mesoscopic superconductors and provide essential guidance for interpreting SMTs and for designing devices based on these systems.