Peakshift characteristics of perpendicular magnetic recording

The characteristics of the peakshift for two Head/Medium combinations of a perpendicular magnetic recording are studied in this paper. One is a combination of a ring head and a single-layer medium, and another is that of a single-pole head and a double-layered medium. Dps20 is defined as the linear density at which the peakshift reaches 20 %, and D50 is defined as the linear density at which the readback voltage is 6 dB below the readback voltage at 1 kBPI. It is shown theoretically that the relation between Dps20 and D50 for these two combinations becomes the same when the phase of the readback voltage for a combination of a ringhead and a single-layer medium is equalized by the Hilbert transformation to that of a combination of a single-pole head and a double-layered medium. This means that about the relation between Dps20 and D50 there is no difference between these two Head/Medium combinations when only the readback from the complete perpendicular recorded magnetization is considered. It is also indicated experimentally that a simple highpass filter is very useful to improve the peakshift without worsening signal-to-noise ratio for the combination of a ring head and a single-layer medium.