Recording studies of perpendicular media leading to 230Gb∕in2

Two media, A and B, are discussed to illustrate the media requirements and properties for the 230Gb∕in2 demonstration. A and B had similar layer structures except that the recording layers had different oxide compositions and that the exchange break layer thicknesses were 21 and 13nm, respectively. They had similar coercivity and intrinsic switching field but showed large difference in writability. Consequently, even though they achieved similar performance for heads down to a track width of 150nm, medium A could not be saturated adequately for heads with a track width of 120nm. On the other hand, medium B possessed the desirable properties for high density recording and formed the base for the media that were used in the 230Gb∕in2 demonstration.