Effects of grain size and intergranular coupling on recording characteristics in CoCrTa media

The effects of grain size on intergranular magnetostatic coupling and on recording characteristics are discussed for the Co/sub 85.5/Cr/sub 10.5/Ta/sub 4/ and Co/sub 78/Cr/sub 17/Ta/sub 5/ thin film media fabricated under the ultra clean sputtering process (UC-process). S/N/sub m/ increases not only with the increment in H/sub c//H/sub k//sup grain/ but also with the decrement in the grain diameter in both CoCrTa media. In media with high H/sub c//H/sub k//sup grain/ value more than 0.35, S/N/sub m/ drastically increases with decrease in the grain diameter, which corresponds to the decrease in the dispersion of magnetic field strength from recorded bits. To maintain high Hc/sub c//H/sub k//sup grain/ value more than 0.35 even in media with small grain size below 10 nm, the selection of alloy composition which gives a small 4/spl pi/M/sub s//H/sub k//sup grain/ value of less than 1.0 is required.