MR head reading characteristics in perpendicular magnetic recording

Reading characteristics of an MR head for perpendicular magnetization are theoretically and experimentally examined. Higher output than with an ordinary longitudinal medium is obtained because of the higher M_st product of the perpendicular medium; D₅₀ is comparable. The step function pulse is confirmed in this experiment too, which is well explained by the reciprocity theorem using numerically calculated head sensitivity function. Differentiation of the signal brings familiar single peak pulses, and improves D₅₀ by about 30%. Signal reproduction from a narrow track of 0.5 μm width is demonstrated with a MR head. Writing head comparison between a thin film ring head and a single pole head is also discussed for the perpendicular double layered medium