Effect of magnetocrystalline anisotropy in single-domain polycrystalline cobalt islands

In this paper we calculate the expected angular distribution of easy axes of magnetization in elongated polycrystalline cobalt single-domain islands. If an island contains only a few hundred polycrystalline grains or less, then the randomly oriented magnetocrystalline anisotropies of the grains are unlikely to completely average out. The resultant net magnetocrystalline anisotropy may be larger than the shape anisotropy for some island geometries, and will lead to an unpredictably oriented net easy axis of magnetization for the entire island. In an array of weakly interacting islands, variations in the orientations of these net easy axes from island to island will lead to variations in magnetic properties such as switching fields and will cause the islands to relax into an unpredictable saturation remanent state after application and removal of a large field.