Analytical approach to the single-domain-to-vortex transition in small magnetic disks

An analytical model to determine the stable configuration of thin ferromagnetic disks as a function of their thickness and diameter is presented. The vortex core energy is fully taken into account. The model includes materials with nonvanishing anisotropy. We find very good agreement with micromagnetic simulations provided that the energy of the finite difference calculation is corrected for the dipolar contribution arising from the discreetness at the edge.