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

The media noise performance is discussed in connection with grain size and intergranular coupling for the Co_85.5Cr_10.5Ta₄, Co₇₈Cr₁₇Ta₅, and Co_62.5Ni₃₀Cr_7.5 thin-film media fabricated under the ultraclean sputtering process (UC process). It is clarified that the value of S/N_m is quantitatively represented as functions of the value of H_c/H_k^grain and the grain size in every kind of media. The value of signal-to-media noise ratio (S/N_m) increases with the increment in H_c/H_k^grain 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/N_m values.