  We developed a micromagnetic method for modeling magnetic systems with
periodic boundary conditions along an arbitrary number of dimensions. The main
feature is an adaptation of the Ewald summation technique for evaluation of
long-range dipolar interactions. The method was applied to investigate the
hysteresis process in hard-soft magnetic nanocomposites with various
geometries. The dependence of the results on different micromagnetic parameters
was studied. We found that for layered structures with an out-of-plane hard
phase easy axis the hysteretic properties are very sensitive to the strength of
the interlayer exchange coupling, as long as the spontaneous magnetization for
the hard phase is significantly smaller than for the soft phase. The origin of
this behavior was discussed. Additionally, we investigated the soft phase size
optimizing the energy product of hard-soft nanocomposites.
