SNR improvement of granular perpendicular recording media

For perpendicular magnetic recording (PMR) media, SNR improvement is more difficult because of the noise contributions from the soft magnetic underlayer (SUL) and the difficulty of achieving grain segregation in the recording layer for low noise. For the SUL, it is important to reduce the spike noise, but also a suitable SUL is needed to achieve a good head field gradient. A recording layer with small grain size, good grain segregation, and large squareness has to be grown on a very thin intermediate layer on the SUL. In this paper, we address some important issues to improve the performance of PMR media through spike noise reduction by adjusting SUL design, improved recording layer SNR, and intermediate layer (IL) modifications for optimum SNR performance.