Dependence of media noise on grain size and intergranular coupling in thin-film media

Abstract

The media noise performance is discussed in connection with grain size and intergranular coupling for the Co85.5Cr10.5Ta4, Co78Cr17Ta5, and Co62.5Ni30Cr7.5 thin-film media fabricated under the ultraclean sputtering process (UC process). It is clarified that the value of S/Nm is quantitatively represented as functions of the value of Hc/Hkgrain and the grain size in every kind of media. The value of signal-to-media noise ratio (S/Nm) increases with the increment in Hc/Hkgrain and also with the decrement in grain size. In the media with grains adequately separated by segregated grain boundaries fabricated by the UC process, grain-size reduction, taking account of the decrease in intergranular magnetostatic coupling, is required to obtain even higher S/Nm values.