Nearly ideal Stoner-Wohlfarth behaviour of coprecipitated barium ferrite powder with reduced packing density

The influence of magnetic interaction on the hysteresis of random assemblies of coprecipitated barium ferrite powders is investigated. For this purpose magnetically diluted samples are prepared by a new preparation method by which particle agglomerations are largely avoided. The static hysteresis properties and the hysteresis of microwave absorption below the natural ferromagnetic resonance frequency are measured as a function of the volumetric packing density p. A substantial increase of the coercivity up to values just below the theoretical coercivity predicted by the Stoner-Wohlfarth model is observed with decreasing ferrite fraction. The hysteresis of microwave absorption shows a significant dependence on p, too. A comparison between measured and calculated absorption curves indicates that the magnetization process of coprecipitated barium ferrite powder corresponds nearly perfectly with the Stoner-Wohl-farth model.