Interactions characterisation in particulate magnetic recording media. Experiments and Preisach model

Abstract

New ways of experimental characterisation of interactions in particulate recording media have been investigated. Experimental procedures to obtain Δ M-like curves (generalised Δ M plots) which are sensitive to both statistical and mean-field interactions between the ferromagnetic particles in the system are analysed. The generalised Δ M plots allow Δ M-like plots to be produced from any reproducible initial remanent state. Another set of experimental curves sensitive to interactions are AC demagnetisation and anhysteretic remanent magnetisation. Measurements were performed on samples in the form of flexible particulate magnetic films (γ-Fe 2O 3 VHS tape and Ba-ferrite dispersed powder films, oriented and not oriented) showing both positive and negative mean-field interaction effects. The experimental results were compared with the simulations made with a scalar generalised moving preisach model. There was good agreement between the theory and experiment for DC remanent magnetisation measurements but the fit was poorer for AC measurements.