Driven particle dispersion in narrow disordered racetracks

TL;DR

This paper analytically and numerically investigates how particles driven in narrow disordered tracks disperse, revealing universal scaling laws for the dispersion constant at high drives, which can characterize disorder in various physical systems.

Contribution

It provides exact analytical expressions for particle velocity and dispersion in disordered tracks and demonstrates the robustness of these results across different models and conditions.

Findings

At large drives, D scales as 1/v for random-field disorder.

At large drives, D scales as 1/v^3 for random-bond disorder.

Universal scaling laws are confirmed across multiple particle and track models.

Abstract

We study the disorder-induced deterministic dispersion of particles uniformly driven in an array of narrow tracks. For different toy models with quenched disorder we obtain exact analytical expressions for the steady-state mean velocity $v$ and the dispersion constant $D$ for any driving force $f$ above a putative depinning threshold. For short-range correlated pinning forces we find that at large drives $D\sim 1/v$ for random-field type of disorder while $D \sim 1/v^3$ for the random-bond type. We show numerically that these results are robust: the same scaling holds for models of massive damped particles, soft particles, particles in quasi-one dimensional or two dimensional tracks, and for a model of a magnetic domain wall with two degrees of freedom driven either by electrical current or magnetic field. Crossover and finite temperature effects are discussed. The universal features we identify may be relevant for describing the fluctuating dynamics of stable localized objects such solitons, superconducting vortices, magnetic domain walls and skyrmions, and colloids driven in quasi one-dimensional track arrays. In particular, the drive dependence of $D$ appears as a sensitive tool for characterizing and assessing the nature of disorder in the host materials.