Demonstration of 35 Gbits/in² in media on glass substrates

A recording density of 35 Gbits/in2 was achieved in longitudinal recording media with high-sensitivity GMR heads. The media displayed excellent thermal stability as a result of a CoPtCrB alloy with high magnetocrystalline anisotropy and relatively narrow grain size distribution. The degree of Co easy-axis orientation in the plane of the film was greatly improved and the grain size was reduced in the media on glass substrates. Estimates of the switching volume from dynamic coercivity and signal-to-noise measurements are larger than the physical grain size, suggesting that intergranular interactions improve stability. A potential path to further increases in recording density above 35 Gbits/in2 is to use antiferromagnetically coupled magnetic layers in the media.