Role of geometrical symmetry in thermally activated processes in clusters of interacting dipolar moments

Abstract

Thermally activated magnetization decay is studied in ensembles of clusters of interacting dipolar moments by applying the master-equation formalism, as a model of thermal relaxation in systems of interacting single-domain ferromagnetic particles. Solving the associated master-equation reveals a breakdown of the energy barrier picture depending on the geometrical symmetry of structures. Deviations are most pronounced for reduced symmetry and result in a strong interaction dependence of relaxation rates on the memory of system initialization. A simple two-state system description of an ensemble of clusters is developed which accounts for the observed anomalies. These results follow from a semi-analytical treatment, and are fully supported by kinetic Monte-Carlo simulations.

arXiv comment9 pages, 6 figures

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Cited by in corpus (4)

• Dipolar-coupled moment correlations in clusters of magnetic nanoparticles
• Self-consistent solution of magnetic and friction energy losses of a magnetic nanoparticle
• Quantifying time in Monte Carlo simulations: application to relaxation processes and AC susceptibilities of magnetic nanoparticles assemblies
• Magnetization Reversal in Two-dimensional Ensemble of Nanoparticles with Positional Defects