Characteristic correlations between the Δm* interaction curves and the Preisach diagram in particulate media

Magnetic interparticle interactions are analyzed by Δm* curves calculated from the initial magnetization curve and the hysteresis loop, instead of the usual deviation Δm based on remanence curves. This study is made on tapes of acicular CrO2 particles and on tapes of CoTi-doped Ba ferrite platelet-shaped particles. The standard Preisach map of the samples is experimentally constructed and the Δm* values, computed from this map, and the values agree fairly well with the Δm* curves measured for the ac demagnetized state and various dc demagnetized states. We describe a procedure for remagnetizing the dc demagnetized samples. For the acicular particles, the peak of the remagnetized curves is lower than that computed from the Preisach map. The opposite occurs for the platelet-shaped particles. This different behavior is ascribed to the different influence of the statistical interaction field and the mean interaction field.