Energy thresholds in the magnetic vortex core reversal

Owing to its small size and high stability, the core of magnetic vortices has been proposed as a possible candidate for binary data storage. We have investigated the energetic aspect of the vortex core reversal in ferromagnetic thin-film elements by means of fully three-dimensional finite-element micromagnetic simulations. The simulations show that the reversal occurs once a well-defined threshold in the exchange energy density is reached. We establish the energetic origin of the core reversal by demonstrating that this threshold corresponds to the energy necessary for the production of a vortex-antivortex pair. The effect of the discretization size on the computed exchange energy of a magnetic singularity is discussed. Such a singularity is required for the core reversal process to unfold.