The influence of geometry and materials choice of the performance of aligned hard-soft nanocomposites is investigated by model calculations. Our analysis of the dimensionality-dependent micromagnetic localization behavior shows that Kneller's original idea of using layered hard-soft structures leads is geometrically much less suitable than three-dimensional configurations (embedded soft spheres). Fixing feature size, geometry, and soft-phase stoichiometry, we find that the achievable energy product is determined by the parameter (M_s - M_h)/K_h, where M_s and M_h are the magnetizations of the soft and hard phases, respectively. Simplifying somewhat, this means that the anisotropy constant of the hard phase is more important than its anisotropy field. Finally, we discuss the effect of residual magnetocrystalline anisotropy in alnico-type permanent magnets.
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