Biased switching of dipolar interacting nanoparticles in a periodic array

We study the switching behavior of a patterned cylinder array in terms of the Landau-Lifshitz-Gilbert equation, including the effect of applied magnetic field, shape anisotropy, crystalline anisotropy, and dipolar interaction between particles. The condition of uncorrelated switching is obtained when the strength of dipolar coupling varies. It shows that a high anisotropy is needed to overcome the strong dipolar interaction in order to ensure the uncorrelated switching. Under the condition of uncorrelated switching, the switching of a single magnetic moment is still much different from the switching of an isolated magnetic moment (without dipolar interaction). The distributions of the critical switching field and switching time of a single magnetic moment for the different configurations of magnetic moments are obtained. By applying a transverse bias field, both the large critical switching field and the switching time can be effectively reduced.