Analysis of DC noise in thin film media

Uniform magnetization (dc) noise is studied using numerically generated arrays of grains. The effects of packing fraction, grain size distribution, and anisotropy orientation are examined. From electron microscopy results, in this initial study, the intergranular grain boundary separation is held fixed. In general, the dc noise increases with increasing grain size distribution and decreases with increasing packing fraction. For a planar random anisotropy distribution, the noise is about an order of magnitude larger than that for well-oriented media. For typical parameters, the dc noise can be less than the transition noise for oriented media and is always significantly larger for planar random media.