Reversal field versus pulse time: theoretical and experimental comparison

A new model of reversal field versus pulse time is used to analyze measurements on elongated particles in magnetic tape. The model applies to all times and temperature and fits the data extremely well. At long times the model agrees with simple Neel-Arrhenius models, but for times less than about 0.1 ms exhibits a progressively increasing switching field. This increase is shown to be due initially to a field dependent attempt frequency. At extremely short times dynamic processes dominate and in this regime the best estimate of the damping constant is obtained. The model gives values of effective volume and anisotropy that are in agrement with nonuniform reversal in these particles