Influence of nano-hole defects and their geometric arrangements on the superfluid density in atomically thin single crystals of indium superconductor

TL;DR

This study investigates how nano-hole defect density and their geometric arrangements in atomically thin indium superconductors influence superfluid density and superconducting properties at both microscopic and macroscopic scales.

Contribution

It reveals the significant impact of defect organization on superconductivity, especially how defect chains can suppress superfluid density and collapse the superconducting gap.

Findings

Superfluid density decreases monotonically with increasing defect density.

Organized defect chains can eliminate superfluid density and superconducting gap.

Minor changes in defect density have limited effect on transition temperature.

Abstract

Using Indium on Si(111) as an atomically thin superconductor platform, and by systematically controlling the density of nano-hole defects (nanometer size voids), we reveal the impacts of defects density and defects geometric arrangements on superconductivity at macroscopic and microscopic length scales. When nano-hole defects are uniformly dispersed in the atomic layer, the superfluid density monotonically decreases as a function of defect density (from 0.7% to 5% of the surface area) with minor change in the transition temperature Tc, measured both microscopically and macroscopically. With a slight increase in the defect density from 5% to 6%, these point defects are organized into defect chains that enclose individual two-dimensional patches. This new geometric arrangement of defects dramatically impacts the superconductivity, leading to the total disappearance of macroscopic superfluid density and the collapse of the microscopic superconducting gap. This study sheds new light on the understanding of how local defects and their geometric arrangement impact superconductivity in the two-dimensional limit.