Perpendicular magnetic recording process of electroless-plated CoNiReP/NiFeP double-layered media with ring-type heads

Electroless-plated CoNiReP/NiFeP double-layered (DL) media with various underlayer coercivities (Hc(u)) were examined to study perpendicular recording performance using ring-type heads. For the case of a DL medium with a combination of ring-type heads, it is found that the enhancement of the reproduced voltage by the phase synchronization (PS) effect is significantly influenced by varying the perpendicular layer thickness (δp) and head parameters. In the recording performance using a Mn-Zn ferrite head, the reproduced voltage is drastically enhanced by the PS effect as far as the head field penetrates sufficiently into the bottom of the DL media and magnetizes the underlayer. In the case of using a metal-in-gap head with Bs=15 kG, the penetration of the head field was further improved