Role of Induced Anisotropy in Magnetic Spectra of Cobalt-Substituted Nickel-Zinc Ferrites

Abstract

Variation of the magnetic spectra with the amount of cobalt ions is measured for samples (35-x)NiO · 8ZnO · xCoO · 57Fe2O3(x=0∼2.5) in the frequency range from 2.5 to 1200MHz. It is shown that the dominant mechanism of the static initial-permeability of the slowly cooled samples changes with the amount of cobalt from displacement of domain wall to rotation of magnetization, and that the contribution of the displacement of domain wall appears again with the change of easy direction by further cobalt substitution. These conclusions are confirmed by the observation of the temperature dependence of the magnetic spectra and the frequency dependence of permeabilities at the remanence, and by a theoretical analysis of the observed magnetic spectra.