Anomalous proximity effect in an inhomogeneous disordered superconductor

TL;DR

This study uses low-temperature STM to reveal a non-uniform superconducting state with spatially varying density of states in an inhomogeneous TiN film, highlighting mesoscopic fluctuations' role in superconductor-normal transitions.

Contribution

It demonstrates a novel non-uniform proximity effect in a disordered superconductor, emphasizing the impact of mesoscopic fluctuations on local electronic states.

Findings

Observation of spatially varying superconducting and normal regions

Identification of a non-standard proximity effect different from conventional models

Evidence supporting the role of mesoscopic fluctuations in superconductor-normal transitions

Abstract

By combining very low temperature scanning tunneling microscopy and spectroscopy on a TiN film we have observed a non uniform state comprising of superconducting (S) and normal (N) areas. The local density of states displays a spatial dependence between S and N different from the usual proximity effect. We conclude that mesoscopic fluctuations might play a major role in accordance with recent theories on superconductor-normal metal quantum transition.