Optimization of Precompensation for NLTS in Perpendicular Magnetic Recording

Nonlinear transition shift (NLTS) and nonlinear amplitude distortion (NLAD) in perpendicular magnetic recording were investigated for CoPtCr-SiO$_2$media with various SiO$_2$contents that have various inter-granular exchange coupling. The tighter inter-granular coupling increases both NLTS and NLAD. The NLTS and NLAD were discriminated and extracted NLTS showed that perpendicular media exhibited the opposite shift to longitudinal media as theoretically expected. Careful precompensation optimization is required to obtain a good error-rate performance at high-linear densities.