Angle-Dependent Switching of Granular and Multilayer Perpendicular Media

Optimal writing of media where full remanent switching is achieved depends on the reversal mechanism and is of interest in designing ultrahigh density magnetic recording systems. Angle-dependent measurements of remanence curves provide a method of determining magnetization reversal mechanisms through comparison with well-known models, such as that due to Stoner and Wohlfarth. The commonly used switching models do not include magnetic viscosity effects and hence only approximate experimental data collected at laboratory times and temperatures. In order to achieve a more accurate comparison to the models and estimate the differences between finite temperature and time-independent data, we have determined the time-independent switching field Hswo(θ) and thermal stability parameter KV/kT(θ) for representative samples from the two classes of media, granular CoCrPt and multilayer Co/Pd, currently under consideration for perpendicular recording. Generalizing the switching field to arbitrary values of magnetization allows the time-independent switching field distribution to be determined and correlated with the fields produced by recording heads.