Evidence of spatial inhomogeneity near the onset of magnetically induced insulating state in superconducting thin films

TL;DR

This paper investigates the non-monotonic differential resistance in magnetically induced insulating thin films, suggesting that spatial inhomogeneities and metallic domains influence the apparent superconductor-metal-insulator transition at low temperatures.

Contribution

It provides evidence that spatial inhomogeneity and metallic domains are key factors in the transition, highlighting the role of inhomogeneities in the insulating state.

Findings

Non-monotonic dV/dI observed in insulating films.

Insulating state may consist of metallic domains connected by point contacts.

Spatial inhomogeneities influence the metal-insulator transition.

Abstract

Non-monotonic differential resistance (dV/dI) is observed in magnetically induced insulating films which exhibit apparent superconductor-metal-insulator transitions in the low temperature limit; at low bias currents the nonlinear transport is insulator-like while at high bias currents it is characteristic of metallic phase. The non-monotonic dV/dI may be evidence that the insulating state consists of metallic domains connected by point contacts (insulating gaps), implying that spatial inhomogeneities play a dominant role in determining the nature of the apparent metal-insulator transition.