Superconductor Insulator Transition in Long MoGe Nanowires

TL;DR

This study investigates the superconductor-insulator transition in ultra-narrow MoGe nanowires, revealing how physical dimensions and magnetic fields influence their quantum phase behavior and localization properties.

Contribution

It provides new insights into the critical role of cross-sectional area and geometry in the superconductor-insulator transition of one-dimensional nanowires.

Findings

Superconductor-insulator transition controlled by wire cross section.

Mean-field critical temperature decreases exponentially with inverse cross section.

Magnetic field can induce a similar transition as physical dimensions.

Abstract

Properties of one-dimensional superconducting wires depend on physical processes with different characteristic lengths. To identify the process dominant in the critical regime we have studied trans- port properties of very narrow (9-20 nm) MoGe wires fabricated by advanced electron-beam lithography in wide range of lengths, 1-25 microns. We observed that the wires undergo a superconductor -insulator transition that is controlled by cross sectional area of a wire and possibly also by the thickness-to-width ratio. Mean-field critical temperature decreases exponentially with the inverse of the wire cross section. We observed that qualitatively similar superconductor{insulator transition can be induced by external magnetic field. Some of our long superconducting MoGe nanowires can be identified as localized superconductors, namely in these wires one-electron localization length is much shorter than the length of a wire.