Hopkinson Effect in Soft and Hard Magnetic Ferrites
J. Sláma, M. Ušáková, M. Šoka, R. Dosoudil and V. Jančárik
Institute of Electrical Engineering, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovičova 3, 812 19 Bratislava, Slovakia
Full Text PDF
The dependences of the susceptibility of selected spinel and hexagonal ferrites on temperature are analyzed. The susceptibility shows a peak just below the Curie temperature TC due to the Hopkinson effect during the heating. The appearance of this effect is associated with a transition from the region of stable magnetization state to superparamagnetic relaxations of the magnetic particles. It is in contrast to other explanations of the Hopkinson effect. These results are compared with measured particles size and with scanning electron microscope micrographs of both types of ferrites.

DOI: 10.12693/APhysPolA.131.762
PACS numbers: 75.50.Gg, 75.30.Kz, 75.30.Cr