Study on initial permeability of Ni-Zn ferrite films prepared by the spin spray method

Initial permeability of Ni-Zn ferrite films prepared by spin spray chemical plating is investigated. They exhibit a semi-hard magnetization process but have relatively high permeability with explicit dual peak resonance loss in the GHz frequency range. In this study, it turned out that the loss is determined mainly by the two magnetic parameters, namely, the crystalline anisotropy and a uniaxial anisotropy induced by Co addition. Measurement of permeability in an external DC field clarified that the semi-hard wall coercivity fixes the spin direction of residual magnetization state and, consequently, gives rise to uniaxial permeability with dependence of its direction on the previously applied DC field.