Insulator superconductor transition on solid inert gas substrates

TL;DR

This paper investigates the insulator-superconductor transition in ultrathin Bi films on inert gas substrates, revealing a robust transition unaffected by substrate screening effects and characterized by inhomogeneous superconductivity.

Contribution

It demonstrates that the insulator-superconductor transition is consistent across different substrates and is best explained by a percolation model, highlighting substrate independence.

Findings

Resistance separatrix near h/4e^2

Crossover thickness approximately 25 Å

Superconductivity appears inhomogeneous

Abstract

We present observations of the insulator-superconductor transition in ultrathin films of Bi on solid xenon condensed on quartz and on Ge on quartz. The relative permeability $\epsilon_{r}$ ranges from 1.5 for Xe to 15 for Ge. Though we find screening effects as expected, the I-S transition is robust, and unmodified by the substrate. The resistance separatrix is found to be close to $h/4e^2$ and the crossover thickness close to 25 $\AA$ for all substrates. I-V studies and Aslamazov-Larkin analyses indicate superconductivity is inhomogeneous. The transition is best described in terms of a percolation model.