Amplitude, density and current correlations of strongly disordered superconductors

TL;DR

This paper studies how strong disorder affects various correlations in superconductors, revealing emergent granularity, island formation, and long-range current correlations, which deepen understanding of disordered superconducting systems.

Contribution

It provides a detailed analysis of static density, amplitude, and current correlations in disordered superconductors, highlighting the emergence of granularity and long-range current paths.

Findings

Strong disorder causes decoupling of density and amplitude correlations.

Superconducting islands enhance density correlations and localize amplitude fluctuations.

Current correlations exhibit long-range behavior due to percolative current paths.

Abstract

We investigate the disorder dependence of the static density, amplitude and current correlations within the attractive Hubbard model supplemented with on-site disorder. It is found that strong disorder favors a decoupling of density and amplitude correlations due to the formation of superconducting islands. This emergent granularity also induces an enhancement of the density correlations on the SC islands whereas amplitude fluctuations are most pronounced in the 'insulating' regions. While density and amplitude correlations are short-ranged at strong disorder we show that current correlations have a long-range tail due to the formation of percolative current paths in agreement with the constant behavior expected from the analysis of one-dimensional models.