The Suppression of Demagnetizing Field Heterogeneity in Ferromagnetic Powders

The two ways of reducing the dispersion of the demagnetizing fields in magnetic powders of cobalt alloys have been tested: the isolation of magnetic particles in nonmagnetic matrix and compaction of the powders. The ferromagnetic resonance (FMR) and the hysteresis loops of the pretreated magnetic powders were investigated. The FMR linewidth is significantly narrowed both with increasing of the nonmagnetic fraction in the samples prepared by the first way and with increasing of relative density of the compacts. The limit case of FMR linewidth in continuous magnetic film there is no dispersion of the demagnetizing fields is in good agreement with discussed data. The hysteresis loops of powder with the particles coated by the non-magnetic phase became narrow and easy saturated with increasing of nonmagnetic phase fraction.