Pattern constraints limiting nonlinear transition shift in high density magnetic recording

Abstract

Nonlinear transition shift (NLTS) produced by the interaction between transitions is a major source of distortions in magnetic recording. NLTS must be reduced to realize higher density and maintain signal quality. However, there is some confusion about the production and behavior of NLTS in previous reports. In this paper, combined with micromagnetic simulation, we have developed a complete theoretical model to predict NLTS on perpendicular magnetic media. The results show that one-level NLTS (caused by one previous transition) will monotonically decrease as the present transition becomes further away from the previous one, and multilevel NLTS (caused by consecutive previous transitions) will firstly increase and quickly approach a constant value as there are more consecutive transitions. Particularly, it is demonstrated that NLTS and its impact on the media signal-to-noise ratio can be significantly limited by pattern constraints.