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

TL;DR

This paper investigates how metallic contacts induce an inverse proximity effect in superconducting nanowires, leading to suppressed critical currents and an anomalous metallic phase, emphasizing the importance of device geometry in superconductor-to-metal transitions.

Contribution

It demonstrates that contact-induced inverse proximity effects and Joule heating, not intrinsic properties, cause the anomalous metallic phase in superconducting nanowires, providing new insights for device design.

Findings

Metallic contacts create weak spots in superconductors.

Inverse proximity effect suppresses critical current.

Joule heating contributes to the metallic phase.

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.