EXPERIMENTAL-STUDY OF NONLINEAR TRANSITION SHIFT IN PERPENDICULAR MAGNETIC RECORDING WITH SINGLE-POLE HEAD

Nonlinear phenomena in perpendicular magnetic recording employing a si ngle-pole head and a double-layered medium were investigated. First, m easurement of linear superposition in the time domain indicated that t he amount of nonlinear transition shift (NLTS) was less than 10 nm. It was concluded that the nonlinearity was caused by transition shift, n ot by waveform distortion. By interpreting the results, we proved that the NLTS was strongly related with head field gradient and interferen ce field from recorded magnetization. Dependence on head parameter was examined by experiments. Based on the results, a single-pole head wit h which transition shift can be reduced was proposed. Pseudo-random se quence analysis revealed that NLTS was several percent even at 318 kFR PI, or at a bit interval of 80 nm, which agreed with the result of mea surement of linear superposition in the time domain analysis. Experime nts showed that NLTS increases the shortest bit length, in contrast wi th the case of longitudinal recording.