WRITING TRANSITION NOISE DUE TO RANDOM PARTICLE DISTRIBUTION IN THIN RECORDING MEDIA

Fluctuations in the magnetization transition due to random distributio n of position, particle size, anisotropy and misorientation of easy ax is of a system of thermally activated noninteracting single domain par ticles (SDPs) in recording media under a recording head field has been analyzed, and the corresponding variance examined, by Monte Carlo sim ulation. Larger values of the thermal factor K upsilon(p)/k(B)T give r ise to steeper magnetization hysteresis curves, narrower transition wi dths and, correspondingly, sharper and narrower noise distributions. H eterogeneous media with an admixture of several different particle siz e distributions lead to a wider transition width at a lower noise leve l. Random anisotropy constant distribution imparts a far more severe e ffect to broaden the transition width while keeping the variance wider and shallower than that due to random particle size distribution. Sim ilarly, random in-plane misorientation distribution of the easy axis i s much less effective to broaden the transition width than that due to the out-of-plane misorientation. Variance in the read-out voltage bec omes asymmetric when the head gap length is comparable to the transiti on width.