Measurement of Down-Track Correlation for Perpendicular Magnetic Media With Various Inter-Granular Exchange Coupling

In order to attain high track density, track-edge noise was studied in conjunction with the fine magnetic structure of perpendicular media. The track-edge noise was increased in media with stronger exchange coupling. The down-track correlation length was measured and compared with the cross-track correlation length. The track-edge noise and correlation length depended upon the inter-granular exchange coupling of the media. Magnetic isolation of grains and steep head field gradient along the cross-track direction is expected to improve the write resolution at the track-edges.