TIME DECAY OF MAGNETIZATION IN LONGITUDINAL COCRTA CR HIGH-DENSITY THIN-FILM MEDIA/

A systematic experimental study of the time decay of the magnetization (M-decay) in longitudinal CoCrTa/Cr high density thin film media with different thicknesses at various levels of in situ reverse magnetic f ield which simulates the demagnetization field in recorded bits is pre sented. Two series of thin film media with the thickness of magnetic l ayer ranging from 90 Angstrom to 1500 Angstrom were deposited by RF/DC magnetron sputtering. The magnetic properties and M-decay were measur ed at room temperature using a vibrating sample magnetometer and an al ternating gradient force magnetometer. The emphasis was placed on the M-decay at various film thickness. It is found that the coefficient of magnetic viscosity is not a constant over 5 decades decay time,(sec.) , the M-decay percentage exhibits a well pronounced peak at the revers e field value of the remanent coercivity, and the mechanism of M-decay is apparently different in thin and thick film recording media. The m echanisms of affecting the magnetic viscosities of thermally-induced t ime decay are explored.