A Superconducting Gap in an Insulator

TL;DR

This study demonstrates the presence of a superconducting energy gap in disordered indium oxide films that are in an insulating state, revealing insights into the superconductor-insulator transition.

Contribution

It provides experimental evidence of a superconducting gap persisting in an insulating phase near the disorder-induced superconductor-insulator transition.

Findings

Superconducting gap observed in insulating indium oxide films.

Gap persists under high magnetic fields.

Similar energy gap scale across different disorder levels.

Abstract

We present tunneling spectroscopy and transport measurements on disordered indium oxide films that reveal the existence of a superconducting gap in an insulating state. Two films on both sides of the disorder induced superconductor to insulator transition (SIT) show the same energy gap scale at low temperatures. This energy gap persists up to relatively high magnetic fields and is observed across the magnetoresistance peak typical of disordered superconductors. The results provide useful information for understanding the nature of the insulating state in the disorder induced SIT.