Superconductivity in the insulating phase above the field-tuned superconductor-insulator transition in disordered indium oxide films

TL;DR

This study investigates the insulating phase of disordered indium oxide films near the superconductor-insulator transition, revealing persistent superconducting correlations at high magnetic fields despite the insulating behavior.

Contribution

It provides new insights into the coexistence of insulating behavior and residual superconductivity in disordered films under high magnetic fields.

Findings

Superconducting fluctuations persist at high magnetic fields.

Insulating phase shows strong amplitude and phase fluctuations.

Superconductivity remains even when pairs are expected to be broken.

Abstract

We study the insulating phase of disordered indium oxide films that undergo a field-tuned superconductor-insulator transition. The transport measurements in a perpendicular magnetic field show distinct regimes of strongly fluctuating order-parameter amplitude and phase, and reveal a wide range of insulator strength in samples with differing disorder, despite the similarity in behavior near the SIT. We characterize the strength of the insulating phase and compare it to the superconducting strength. We find that the films do not return to the expected normal state even at high perpendicular magnetic fields where all pairs should be broken, suggesting the remaining presence of superconductivity at high fields.