Formation kinetics of magnetic chains, rings, X's, and Y's

TL;DR

This study investigates the formation and evolution of magnetic particle structures in a monolayer, revealing how different motifs emerge at various densities and proposing a defect-driven phase separation mechanism.

Contribution

It provides detailed simulation-based insights into the kinetics of magnetic structure formation and introduces a defect mechanism for metastable phase separation in two dimensions.

Findings

Low-density structures are mainly chains and rings.

High-density structures include labyrinthine networks.

Transient Y- and X-shaped defects are observed at intermediate densities.

Abstract

The kinetics of aggregation in a monolayer of magnetic particles are studied using stochastic dynamics computer simulations. At low densities (<8% coverage) the equilibrium structure is made up of chains and rings; the primary mechanisms by which these motifs form are described. At higher densities (>15% coverage), we observe large transient concentrations of Y-shaped and X-shaped defects that ultimately give way to an extended, labyrinthine network. Our results suggest that a defect mechanism -- such as that proposed by Tlusty and Safran, Science 290, 1328 (2000) -- could drive a metastable phase separation in two dimensions.