Non-Gaussian tail in the force distribution: a hallmark of correlated disorder in the host media of elastic objects

Jazmín Aragón Sánchez,Raúl Cortés Maldonado,Gladys Nieva,Alejandro B Kolton,Néstor René Cejas Bolecek,Moira I Dolz,Yanina Fasano,Joaquín Puig,Marcin Konczykowski,Pablo Pedrazzini,Cornelis J Van Der Beek,Gonzalo Rumi

doi:10.1038/s41598-020-76529-w

Abstract

Inferring the nature of disorder in the media where elastic objects are nucleated is of crucial importance for many applications but remains a challenging basic-science problem. Here we propose a method to discern whether weak-point or strong-correlated disorder dominates based on characterizing the distribution of the interaction forces between objects mapped in large fields-of-view. We illustrate our proposal with the case-study system of vortex structures nucleated in type-II superconductors with different pinning landscapes. Interaction force distributions are computed from individual vortex positions imaged in thousands-vortices fields-of-view in a two-orders-of-magnitude-wide vortex-density range. Vortex structures nucleated in point-disordered media present Gaussian distributions of the interaction force components. In contrast, if the media have dilute and randomly-distributed correlated disorder, these distributions present non-Gaussian algebraically-decaying tails for large force magnitudes. We propose that detecting this deviation from the Gaussian behavior is a fingerprint of strong disorder, in our case originated from a dilute distribution of correlated pinning centers.

Highlights

Inferring the nature of disorder in the media where elastic objects are nucleated is of crucial importance for many applications but remains a challenging basic-science problem
Even though the snapshots are taken at 4.2 K, the vortex structure observed by means of magnetic decoration is frozen at temperature Tfreez >> 4.2 K given by disorder inhibiting vortex motion at lengthscales larger than the vortex spacing[53,63]
Once Tfreez for a given host medium is determined, the particle-particle interaction force per unit length for a given vortex i with the rest of the j-th vortices of the structure can be computed a s12 fi(ri) =

Summary

Introduction

Inferring the nature of disorder in the media where elastic objects are nucleated is of crucial importance for many applications but remains a challenging basic-science problem. Vortex structures nucleated in point-disordered media present Gaussian distributions of the interaction force components. With the aim of inferring the nature of disorder in the host medium from physical properties of the elastic objects, in this work we follow a novel approach and study the inhomogeneous spatial distribution of the particle-particle interaction force in extended fields-of-view. We study samples with different types of pinning landscapes representative of different classes of randomly distributed disorder: Naturally occurring weak and dense point pins in pristine samples, extra moderate and dense point pins generated by electron irradiation, and columnar-defects (CD) responsible for correlated pinning In the latter case, the pinning centers are columns of crystallographic defects generated via heavy-ion irradiation, that traverse the whole sample thickness and are distributed at random in the plane perpendicular to the direction of vortices. This work presents a comprehensive corpus of data in Bi2Sr2CaCu2O8+δ samples with a diversity of pinning centers with different nature and spatial density

Methods

Results

Discussion

Conclusion