Monte Carlo simulations of interaction effects on magnetic viscosity in ferromagnetic granular media

C G Verdes, B R Diaz, R W Chantrell, S Thompson, A Stancu

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A Monte Carlo time and temperature dependent model was developed to simulate magnetization processes in fine ferromagnetic particle media. The model uses a combination between a time dependent Stoner-Wohlfarth model and a standard Metropolis algorithm to find the magnetization of single-domain particle systems. Both magnetostatic and exchange interactions are introduced explicitly.

Variation of magnetic viscosity with interactions and temperature is studied. Results show that viscosity exhibits a maximum around coercive field. The value of this maximum is closely related to the strength and the origin of interactions as well as to temperature. Dipolar interactions decrease the viscosity and broaden the viscosity vs. field curve, while exchange interactions lead to an increase in viscosity around coercive field. An increase in temperature up to the critical temperature for the superparamagnetic behavior leads to an increase in viscosity. Further increase of temperature produces a decrease in viscosity.

Original languageEnglish
Pages (from-to)251-256
Number of pages6
JournalInternational journal of applied electromagnetics and mechanics
Issue number1-4
Publication statusPublished - 2001

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