Effects of particle size on read/write properties of Ba ferrite and Co-γFe 2O 3 coated media

Abstract

The effects of particle size on the read/write properties in Ba ferrite and Co-γFe 2O 3 particulate rigid disks are described and compared. We have already reported that the half-width of isolated pulses (PW 50) in Co-γFe 2O 3 disks decreased as the particle size became smaller. In Ba ferrite disks, however, PW 50 does not decrease as the particle size becomes smaller, that is, as the specific surface area (SSA) increases. 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 length. The PW 50 of Ba ferrite disks is smaller than that of Co-γFe 2O 3 disks. The small PW 50 values of the Ba ferrite disks, compared with those of Co-γFe 2O 3 disks, can be explained by the small SFD values and the thinness of Ba ferrite particles. The decreasing slope of the signal-recorded noise with increasing recording density in Ba ferrite disks is smaller than that in Co-γFe 2O 3 disks. The peak height or dip depth of the reverse dc-erase noise in Ba ferrite disks is also smaller than dip depth in Co-γFe 2O 3 disks.