Micromagnetic simulations of polycrystalline cobalt islands for patterned media

The magnetization state and the switching field of single domain polycrystalline islands (40 nm×80 nm×10 nm) were investigated by micromagnetic simulations. In this work, the crystalline orientations of the grains forming the islands were randomly chosen from a Gaussian distribution, centered along the in-plane short axis of the island. The remanent magnetization was shown to be parallel to the in-plane short axis when the standard deviation σ of the distribution is below 30 degrees. The highest coercivity of an assembly of 100 individual islands was found to be between 3100 and 3700 Oe when σ is as low as 10 degrees and the islands comprise 512 grains. Such an array is promising as recording media for densities beyond 100 Gb/in²