PREPARATION AND CHARACTERISTICS OF CO-ZN FERRITE RIGID DISKS WITHOUT PROTECTIVE LAYERS FOR HIGH-DENSITY RECORDING

Spinel type of Co-Zn ferrite films were deposited on glass ceramic dis k substrates of 1.89 inch diameter by using a facing targets sputterin g apparatus without post-annealing process. Films deposited at substra te temperature T-s of 200 and 400 degrees C were composed of crystalli tes with clear (111) and (311) orientation, respectively. Disks with ( 111) orientation (Disk(lll)) possessed larger perpendicular component of magnetization than that with (311) orientation (Disk(311)). The cen ter-line average roughness R-a of Disk(lll) and Disk(311) were 1.1 and 4.0 nm, respectively. Their read/write characteristics were examined without protective layer by using a merged type of magnetoresistive (M R) head with shield gap length of 0.27 mu m. The linear recording dens ity D-50 increased with decrease of the thickness of recording layer f or both disks and the highest D-50 was 136 kfrpi for Disk(lll) 50 nm t hick and 86 kfrpi for Disk(311) 35 nm thick, respectively.