Indirect reversal of vortex core polarity in magnetically dynamic coupled disks

Many authors have recently investigated low-dimension magnetic systems, in particular systems that form magnetic vortices in their equilibrium magnetic configuration. The dynamic behavior of magnetic vortices has been studied extensively. A vortex core displaced from its equilibrium position, returns to this position performing a gyrotropic motion. This motion´s eigenfrequency (ω₀) depends on the ratio of the thickness to the radius of the disk β=L/R. For small thickness disks ω₀ ≈ 20/9 γ M_s β, where γ is the gyromagnetic ratio and M_s is the saturation magnetization of the disk material. The switching of vortex cores polarity has deserved special attention in the literature. For example, the polarity can be inverted through the application of pulsed in-plane fields, polarized spin currents and so on. Rotating magnetic fields at ω₀ are particularly effective in performing this inversion. The influence of uniaxial perpendicular anisotropy (PMA) on the dynamics of vortex cores has not yet been extensively investigated.