Signal to Noise Ratio of Thin Film Disks with Various Orientation Ratios

Thin film disks with various orientation ratios (OR) ranging from 0.5 to 4.3 were fabricated by sputter deposition of CoPtCr with Cr underlayers onto preheated NiP/AI-Mg disks. The recording characteristics of these disks were investigated using a thin film head. The isolated pulse signal amplitude to media noise ratio (So/N) increased when OR was increased from 0.5 to 1 and then remained relatively constant for OR ≥ 1. An improvement of about 10 dB in overwrite of the disks with OR > 1 was observed. © 1990 IEEE