INTERPARTICLE INTERACTIONS AND PREISACH DIAGRAMS IN FERRITE PARTICULATE MEDIA

摘要

The standard Preisach diagram of Ba ferrite particulate media is experimentally constructed by a sequence of magnetization variations starting from the ac demagnetized state. The interparticle interactions, evaluated by the quantity Am* (defined in the text), are deduced from this diagram for demagnetized states obtained by different ac and dc procedures. The results of this evaluation agree fairly well with those directly obtained by measuring the initial magnetization curve and the hysteresis loop. The positive or negative values of Δm~* are illustrated on the basis of the magnetic moment distribution in the Preisach map. Finally, a method is described for remagnetizing the samples by an ac decreasing field starting from the different dc demagnetized states. From a comparison between the remagnetized curves so obtained and those deduced from the Preisach map it is pointed out the different influence of the statistical interaction field and the mean interaction field usually considered for describing the interparticle interactions.