Readback model for double layer perpendicular recording media

A readback model is developed to study characteristics of perpendicular recording media with a soft underlayer. The model is applied to an experimental perpendicular recording media represented by Voronoi cells. The readback voltage from this model shows dependence both on the transition length and the fly-height separately. A roll-off curve produced from reading continuous, perfect arctangent transition media is compared to experimental results to obtain the transition length and the fly height. The calculated autocorrelation signal to noise ratio (SNR) from the model with Voronoi grain based media compared to those obtained from a particular example shows cluster forming with areas equal to about three times the grain size. This reduces the media SNR by about 4.7 dB. This readback model therefore allows SNR measurement to be converted to detailed understanding of the media structure.