Magnetic vortex gyration in a confined double-nanocontacts structure

We studied the gyrotropic motion of a vortex in a double-contacts system, where two spin-polarized out-of-plane dc currents were injected into a nanodisk through a centered nanocontact and an off-centered nanocontact, respectively. Driven by the two currents, the orbit of vortex core distorts. Moreover, the gyrotropic frequency shows zigzag variation with time when the off-centered current passes from −z to +z-axis, and a peak appears when the off-centered current passes from +z to −z-axis. We analyzed the forces acting on the vortex core, and found that the changes of frequency mainly attribute to the forces generated by the Oersted fields arising from the two currents.