Transport Phase Diagram of Homogeneously Disordered Superconducting Thin Films

TL;DR

This study maps the phase diagram of disordered superconducting tantalum thin films, revealing that a direct transition from superconductor to insulator is prevented by an intervening metallic phase, based on nonlinear transport analysis.

Contribution

It provides the first comprehensive phase diagram in temperature-magnetic field-disorder space for homogeneously disordered superconducting films, highlighting the role of the metallic phase.

Findings

Superconducting phase is surrounded by a metallic phase at all disorder levels.

Direct superconductor-insulator transition is absent at any disorder.

Nonlinear transport characteristics uniquely identify different phases.

Abstract

We have constructed a phase diagram in temperature-magnetic field-disorder space for homogeneously disordered superconducting tantalum thin films. Phases are phenomenologically identified by the nonlinear transport characteristics that are unique in each phase. The resulting phase diagram shows that a direct superconductor-insulator transition is prohibited at any disorder because the superconducting phase is completely surrounded by the intervening metallic phase.