Static computational micromagnetism of demagnetization processes in nanoscaled permanent magnets

Micromagnetic calculations using the finite-element method provide a quantitative understanding of demagnetization processes in nanocrystalline ferromagnetic materials. In these materials demagnetization processes are mainly determined by short-range exchange and long-range dipolar interactions, which sensitively depend on microstructural properties. To reveal the relations between intergrain interactions, microstructure and magnetic properties like remanence and coercive field, we calculated the demagnetization curves for different three-dimensional grain structures as a function of the mean grain diameter: Starting from a single sphere, we successively constructed regular grain structures with increasing number of grains. The most complex grain arrangement consists of an ensemble of 35 isotropically distributed grains with disturbed surfaces. \textcopyright{} 1996 The American Physical Society.