Analytical DC Noise Models for Granular Perpendicular Media

Analytical derivations for the DC signal and DC noise of perpendicular granular media are presented. The DC noise models are based on the binomial statistics of the grains’ magnetic orientations, most of them being up/down out-of-plane yet enabling the statistical occurrence of grains with in-plane anisotropy. The models also include considerations for irregular grains positions, variations of grains area and saturation magnetization, and account for readers with arbitrary two-dimensional sensitivity functions. Analytical expressions are validated by comparison to numerical simulations. Model predictions of the temperature dependence of the noise power for Heat Assisted Magnetic Recording (HAMR) media, corresponding to the THMap measurements, are also presented.