SOME OF THE MAGNETIC-PROPERTIES OF POLYCRYSTALLINE SOFT FERRITES - ORIGINS AND DEVELOPMENTS OF A MODEL FOR THE DESCRIPTION OF THE QUASI-STATIC MAGNETIZATION

Since the first laws discovered by Lord Rayleigh in 1887, the literatu re has given a spectacular number of works in the magnetisation modeli ng field. The authors remark that most of these works are devoted to s oft magnetic metals with intent to improve the knowledge of the dynami c power losses (anomalous losses), and that only a few models have rea lly been developed on true physical considerations. In the soft ferrit es area, Globus has proposed a model of magnetisation based on the mot ions (reversible bulgings and irreversible movements of translation) o f a single 180 degrees domain wall contained in an ideal spherical gra in. The authors discuss the main assumptions of this model with regard to their own practical experience of soft ferrites (actions of extern al anisotropies), and also to some particular results published by oth er workers. In the last part of this paper, a new progress on the Glob us model is presented which concerns the hysteresis simulation. The re sult is tested on actual hysteresis loops of different shapes.