AN ANALYSIS OF MAGNETIZATION PROCESSES IN METAL EVAPORATED TAPE

Metal evaporated (ME) tape shows excellent recording performance at high recording densities. According to its microstructure, ME tape has a tilted anisotropy axis which is directed neither in film plane nor perpendicular to it. Due to the nonvanishing perpendicular magnetization component conventional single axis measurements of hysteresis are strongly influenced by film demagnetization. It is shown that conventional hysteresis data completely mask the true magnetic properties of ME tape. For a true demagnetization correction a continuous adjustment of the external field and its angle during measurement has to be accomplished. Using a self-consistent iteration scheme compensated hysteresis as well as remanence curves are measured. These data reveal that the ME tape resembles a particulate medium which is highly oriented and has an extremely narrow switching field distribution. The magnetization reversal process is incoherent with a strong increase of switching fields at high angles between the field and the intrinsic easy axis which is located at an angle of 38-degrees to the film plane. It is shown that thermal activation has a strong influence on the measured data.