Comparison of time-decay of read-back signals in keepered and non-keepered media

Soft sendust keeper layer has been sputtered on top of longitudinal thin film media which has an M/sub r/t value of 0.49 memu/cm/sup 2/. Measurements of time-decay in both keepered and non-keepered longitudinal thin film media have been performed on a spin-stand tester. Experimental results showed that time-decay is larger in tested media which has lower M/sub r/t values compared to those that have a larger M/sub r/t of 1.26 memu/cm/sup 2/. A 50 /spl Aring/ thick sendust keepered media has about half the decay rate compared to its non-keepered counterpart (M/sub r/t=0.49 memu/cm/sup 2/) at a recording density of 6000 fr/mm. Also, it was found that time-decay in 100 /spl Aring/ and 150 /spl Aring/ thick keepered media is less than that in a 50 /spl Aring/ keeper media.