Perpendicular recording characteristics and microstructure for electroless plated conirep flexible disks with a nimop underlayer

Two kinds of electroless-plated CoNiReP / NiMoP flexible disks were investigated from the viewpoint of forming a perpendicular recording medium containing an initial in-plane layer. The well-oriented hcp phase of the c-axis normal to the film plane grew spontaneously in the perpendicular anisotropic layer after depositing the in-plane initial layer, which was composed of anfcc phase. In such a medium, the in-plane coercivity of an in-plane anisotropic initial layer was controlled as 50 and 85 Oe by changing the bath factor of NiS04concentration to 0.10 and 0.06 mol dm- 3, respectively. Although the switching mechanism of the CoNiReP film had been clarified as a rotation, that of both the in-plane anisotropic initial layers was dominated by wall motion. The reproduced voltage of the medium with the in-plane anisotropic initial layer whose coercivity was 50 De was higher than that of the initial layer whose coercivity was 85 De according to the larger double layer effect. The medium with a quasi-soft magnetic in-plane anisotropic initial layer of a wall motion appeared to show excellent recording characteristics by using ring-type heads.