Anti-hyperuniform diluted vortex matter induced by correlated disorder

TL;DR

This study reveals that vortices in a superconductor with correlated defects form an anti-hyperuniform disordered structure, contrasting with hyperuniform arrangements in point-disorder samples, influenced by interactions and out-of-equilibrium conditions.

Contribution

It demonstrates the emergence of anti-hyperuniform vortex structures due to correlated disorder and out-of-equilibrium effects in a superconductor, supported by imaging and simulations.

Findings

Vortices in correlated-disorder samples are anti-hyperuniform.

Point-disorder samples exhibit hyperuniform vortex arrangements.

Numerical simulations explain the anti-hyperuniformity through interactions and quenched disorder.

Abstract

Disordered hyperuniform materials are very promising for applications but the successful route for synthesizing them requires to understand the interactions induced by the host media that can switch off this hidden order. With this aim we study the model system of vortices in the $\beta$-Bi$_2$Pd superconductor where correlated defects seem to play a determinant role for the nucleation of a gel vortex phase at low densities. We directly image vortices in extended fields-of-view and show that the disordered vortex structure in this material is anti-hyperuniform, contrasting with the case of vortex structures nucleated in samples with point-like disorder. Based on numerical simulations, we show that this anti-hyperuniform structure arises both, from the interaction of a diluted vortex structure with a fourfold-symmetric correlated disorder quite likely generated when cleaving the samples and from the out of equilibrium nature of the quenched configuration.