On the effect of a nonuniform magnetization profile on the readback process in vertical recording

Abstract

The effect of a nonuniform magnetization profile on the output of a Karlquist ring head and single-layer vertical medium is explored. Assuming a linear decrease in magnitude of the magnetization with depth into the medium, an exact analytical expression for the output of a Karlquist ring head is derived and used as the basis for numerical calculations of the readback amplitude, pulsewidth, frequency response, peakshift, and read spacing loss. It is shown that the peak-to-peak pulsewidth and frequency response can be described by a modification of the standard formula for the corresponding longitudinal medium parameters. A comparison between longitudinal and vertical recording technologies is made for both rigid and flexible media parameters using these results. Finally, the effect of the nonuniform magnetization on readback spacing loss is examined and the implications with respect to reported experimental spacing loss measurements are discussed.