FMR and IR of high permeability ferrites

The ferromagnetic resonance (FMR) and infrared spectra (IR) of polycrystalline MnZn ferrite have been studied for samples with high permeability (∼10000) and low permeability (∼4000) values to investigate the origin of physical processes which result in permeability enhancement. Two resonance peaks are observed for all the samples in the FMR spectrum. The main resonance and the secondary resonance show different temperature dependence for high and low μ samples. The relative intensities of the recorded IR spectrum are also observed to be characteristic of the sample permeability. These results have been explained on the basis of a Fe²⁺ion, oxygen vacancy pair which contributes to a positive single ion anisotropy and leads to anisotropy compensation.