Magnetic losses versus sintering treatment in Mn-Zn ferrites

Mn-Zn ferrites prepared by different sintering schedules at 1325°C, 1340°C, and 1360°C, have been characterized from the structural, electrical, and magnetic viewpoint. Magnetic losses and complex permeability have been, in particular, measured and analyzed from quasi-static excitation up to 1GHz. It is observed that lower sintering temperatures and shorter treatment times lead to more homogeneous grain structure and better soft magnetic response at all frequencies. It is shown, however, that, once the contribution by eddy currents is singled out, the energy losses tend to coincide beyond a few MHz in the differently treated samples. The interpretative approach consists in separating the contributions by the domain wall displacements and the magnetization rotations to complex permeability and losses as a function of frequency. This can be accomplished in a relatively simple way in the low induction region described by the Rayleigh law, where these quantities can be quantitatively related and the linear Landau-Lifshitz-Gilbert equation applies, account being taken of the distribution in amplitude and orientation of the local anisotropy fields. •DC-1GHz magnetic losses and complex permeability of Mn-Zn ferrites are analyzed.•Contributions by domain wall displacements and rotations are separately obtained.•Energy losses caused by eddy currents and spin damping are separately identified.•Microstructure is shown to chiefly affect the domain wall processes.•Rotational permeability and loss are predicted through Landau-Lifshitz equation.