A Model for Noise Power Nonlinearities in Perpendicular Magnetic Recording

Noise power versus linear density is modeled focusing solely on the magnetization fluctuations. The model examines the effect of mid-to high-density trunctation of the recorded magnetization transitions. At these densities, the medium becomes increasingly erased and the low density linear noise slope can vanish or even change sign. The slope of the total noise power versus density depends on a tradeoff of decreasing transition noise and increasing (AC) erasure noise. At high densities, the noise becomes dominated by the large medium erasure noise. The role of head-medium parameters is illustrated.