On the perpendicular recording process

An analytical model of the recording process is used to examine the factors that influence the recorded magnetization. If the ‘‘switching’’ occurs at the top of the medium, the magnetizaton is influenced mostly by the head-medium separation. If the ‘‘switching’’ occurs at the middle of the medium, the magnetization is influenced by the head-medium separation, the slope loop of the M-H at M=0, and the medium thickness. The magnetization is asymmetrical in both cases and the asymmetry translates into asymmetrical readback waveforms.