NOISE PROPERTIES OF MULTILAYERED CO-ALLOY MAGNETIC RECORDING MEDIA

This report presents the results of medium noise characterization of multilayered magnetic recording films having thin nonmagnetic isolation layers. We have found a substantial reduction of all types of medium noise for several Co-alloys when multilayered. This reduction in noise power is approximately proportional to l/(number of magnetic layers) but also depends on film thickness and other factors. The primary cause of the reduction is evidently the breaking of exchange between magnetic layers. It is also found that the intrinsic noise power per unit (Mrξ)2varies with film thickness, more in some alloys than in others, altering the noise reduction for multilayers. Evidence also suggests that magnetostatic interactions between layers further reduce the noise power. A phenomenological model explaining the observed effects is presented. The evidence demonstrates that a similar effect would be observed in any metal film recording media. © 1990 IEEE