Temperature dependence of complex permeability and power losses for Mn–Zn ferrites

Abstract

The complex permeability and power losses are very important parameters for soft magnetic materials. In this paper, the temperature dependence of these two parameters is investigated for Mn–Zn ferrite. The Hopkinson peak was observed at 440 K below the Curie temperature (TC), and the domain-wall resonance peaks and the natural resonance peaks gradually move to lower frequencies until the Hopkinson temperature (TH). Further, the domain-wall resonance peaks from relaxation type to resonance type are observed by fitting the permeability spectrum, which is related to the reduction of the loss factor. In addition, the power losses were measured from 245 to 365 K and divided into hysteresis loss (Ph), eddy current loss (Pe), and excess loss (Pexc). Each loss contribution was discussed to be dependent on temperature. The results show that at high temperatures and high frequencies, the thermal superposition effect will cause an abnormal increase in excess loss.