Micromagnetic Predictions for Signal and Noise in Barium Ferrite Recording Media

A dynamic, micromagnetic recording process simulation is used to predict signal and noise for barium ferrite media. The model has high spatial (particulate level) and temporal (~ 10 ' s) resolution. The theory includes head saturation, image charge, particle magnetostatic interactions, and particle anisotropy. Most input media and head characteristics are taken from direct measurements, such as electron microscopy or magnetometry, or from the literature. However, several variables, such as head-medium spacing, can only be estimated from the available data; errors in these estimates could affect the predicted numbers by several dBV. Overall, the calculations yield very high accuracy; both signal and bulk erase noise match experiment to within ~1 dBV. This unusually close agreement for the bulk erase noise is obtained without the benefit of particle-particle interactions. This latter point places barium ferrite in interesting contrast to acicular particle media where interactions are believed to substantially reduce short-wavelength bulk erase noise.