Nonlinear effects of transition broadening

Nonlinear broadening of closely spaced transitions has been studied using micromagnetics simulations. Results show a large increase in the width of a transition due to the demagnetizing field effect of earlier transitions. Based on this observation, a simple recording channel model is developed to investigate the effects of nonlinear transition broadening on detection performance. This analysis shows that the conventional peak detector is much less sensitive to the detrimental effects of nonlinearity than the more advanced partial response maximum likelihood (PRML) scheme, mainly due to the extra transition spacing provided by the minimum run-length-limited constraint. This result suggests that in order to preserve the improved signal detection capability of advanced signal processing schemes like PRML, reduction of nonlinearity is essential in the media design