Arrangement effects of nanocontacts on the magnetic vortex gyration in a confined multi-nanocontacts structure

We studied the gyrotropic motion of a magnetic vortex in a multi-nanocontacts system, where spin-polarized out-of-plane dc currents were injected into a nanodisk through a centered nanocontact and several circle-distributed off-centered nanocontacts. It was found that the number of the off-centered nanocontacts, the direction combination of the currents, the current density, and the distance between the centered and the off-centered nanocontact all influence the gyrotropic motion of vortex, including vortex core orbits, eigenfrequency, and instantaneous gyrotropic frequency.