Spin current induced dynamics and polarity switching of coupled magnetic vertices in three-layer nanopillars

We study dynamics of two magnetostatically coupled magnetic vortices excited by spin-polarized electrical current in a nanopillar consisting of permalloy magnetic layers with different thickness separated by a nonmagnetic spacer. We demonstrate three dynamical regimes of the vortices bound motion: damped oscillations, stationary oscillations and a regime of the polarity switching of one of the vortices; the critical currents for each dynamical phase are identified. The structure and trajectory of the vortex core motion in each magnetic layer are studied for the case of the vortex polarity switching in a thick layer. We show that the vortex polarity switching process has a dynamic nature and is associated with a vortex-antivortex pair formation.