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 disk substrates of 1.89 inch diameter by using a facing targets sputtering apparatus without post-annealing process. Films deposited at substrate temperature T_s of 200 and 400°C were composed of crystallites with clear (111) and (311) orientation, respectively. Disks with (111) orientation (Disk(111)) possessed larger perpendicular component of magnetization than that with (311) orientation (Disk(311)). The center-line average roughness R_s of Disk(111) 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 (MR) head with shield gap length of 0.27 μm. The linear recording density D₅₀ increased with decrease of the thickness of recording layer for both disks and the highest D₅₀ was 1.36 kfrpi for Disk(111) 50 nm thick and 86 kfrpi for Disk(311) 35 nm thick, respectively