Enhancing long-range order in disordered two-band s-wave superconductors

TL;DR

This paper studies how hybridization in disordered two-band s-wave superconductors can sustain long-range order despite disorder, revealing the formation of superconducting islands with correlated local order.

Contribution

It demonstrates that hybridization can counteract disorder effects, maintaining long-range superconducting order in a two-band model, relevant for real materials under pressure or doping.

Findings

Disorder weakens superconductivity, but hybridization promotes it.

Hybridization helps preserve long-range order against disorder.

Superconducting islands with correlated local order parameters form at high disorder.

Abstract

We investigate the effects of disorder in a hybridized two-dimensional two-band s-wave superconductor model. The situation in which electronic orbitals form these bands with angular momentum such that the hybridization $V_{i,j}$ among them is antisymmetric, under inversion symmetry, was taken into account. The on-site disorder is given by a random impurity potential $W$. We find that while the random disorder acts to the detriment of superconductivity, hybridization proceeds favoring it. Accordingly, hybridization plays an important role in two-band models of superconductivity, in order to hold the long-range order against the increase of disorder. This makes the present model eligible to describe real materials, since the hybridization may be induced by pressure or doping. In addition, the regime from moderate to strong disorder, reveals that the system is broken into superconductor islands with correlated local order parameters. These correlations persist to distances of several order lattice spacing which corresponds to the size of the SC-Islands.