Writing transition noise due to random particle distribution in thin recording media

Fluctuations in the magnetization transition due to random distribution of position, particle size, anisotropy and misorientation of easy axis of a system of thermally activated noninteracting single domain particles (SDPs) in recording media under a recording head field has been analyzed, and the corresponding variance examined, by Monte Carlo simulation. Larger values of the thermal factor Kvp/kBT give rise to steeper magnetization hysteresis curves, narrower transition widths and, correspondingly, sharper and narrower noise distributions. Heterogeneous media with an admixture of several different particle size distributions lead to a wider transition width at a lower noise level. Random anisotropy constant distribution imparts a far more severe effect to broaden the transition width while keeping the variance wider and shallower than that due to random particle size distribution. Similarly, random in-plane misorientation distribution of the easy axis is much less effective to broaden the transition width than that due to the out-of-plane misorientation. Variance in the read-out voltage becomes asymmetric when the head gap length is comparable to the transition widt