Soft Magnetic Properties of Thin Nanocrystalline Particles Due to the Interplay of Random and Coherent Anisotropies

We investigated coercive fields of 200 nm × 1200 nm × 5 nm rectangular nanocrystalline thin films as a function of grain size D using finite-element simulations. To this end, we created granular finite-element models with grain sizes ranging from 5 to 60 nm, and performed micromagnetic hysteresis calculations along the y-axis (easy direction) as well as along the x-axis (hard direction). We then used an extended random anisotropy model to interpret the results and to illustrate the interplay of random anisotropy and shape-induced anisotropy, which is coherent on a much larger scale, in thin films.