Effect of Tartronic Acid on Magnetic Properties of Electroless Plated Co-Ni-Re-P Alloy Films for a Perpendicular Recording Medium

Abstract

Electroless plated Co-Ni-Re-P alloy films for perpendicular recording medium were investigated and developed. It was found that the addition of tartronic acid into the plating bath makes it possible to form the Co-Ni-Re-P perpendicular anisotropy films with noMnSO₄ present. The Co-Ni-Re-P alloy film whose composition is simpler than that of the previously developed Co-Ni-Re-Mn-P films, has a higher potential than that of Co-Ni- Re-Mn-P alloy film from a practical use viewpoint as a perpendicular recording media. Readlwrite characteristics of 8 inch disks using Co-Ni-Re-P medium were also obtained and measured with a combination of a ring head. Characteristics whose quality was almost equal to those of Mn codeposited media were obtained, and a higher recording density would be expected with improvement in the matching condition between head and disk properties. The recording density of 54 kFRPI as D₅₀ was obtained with 0.02 μm thick magnetic medium using a 0.33 μm gap length ring head at 0.12 μm head-medium spacing.