EFFECTS OF PARTICLE-SIZE ON READ WRITE PROPERTIES OF BA FERRITE AND CO-GAMMA-FE2O3 COATED MEDIA

The effects of particle size on the read/write properties in Ba ferrit e and Co-gammaFe2O3 particulate rigid disks are described and compared . We have already reported that the half-width of isolated pulses (PW5 0) in Co-gammaFe2O3 disks decreased as the particle size became smalle r. In Ba ferrite disks, however, PW50 does not decrease as the particl e size becomes smaller, that is, as the specific surface area (SSA) in creases. The SSA independence is caused by the fact that the thinness of the Ba ferrite particles along the easy axis of magnetization, the thickness direction, is much thinner than that along the transition le ngth. The PW50 of Ba ferrite disks is smaller than that of Co-gammaFe2 O3 disks. The small PW50 values of the Ba ferrite disks, compared with those of Co-gammaFe2O3 disks, can be explained by the small SFD value s and the thinness of Ba ferrite particles. The decreasing slope of th e signal-recorded noise with increasing recording density in Ba ferrit e disks is smaller than that in Co-gammaFe2O3 disks. The peak height o r dip depth of the reverse dc-erase noise in Ba ferrite disks is also smaller than dip depth in Co-gammaFe2O3 disks.