Steady vortex gyrotropic motion driven by an out-of-plane spin-polarized current in a confined nanocontact structure

We studied the steady vortex gyrotropic motion in a Permalloy nanodot driven by an out-of-plane spin-polarized current which is injected through a nanocontact. First, we calculated the current density range in which the vortex steady motion can exist. It is found that both the nanocontact dimensions and dot aspect ratios have influence on it. Then the orbital radius and oscillation frequency of the steady motion in the plane of current density and nanocontact radius were diagramed. It indicated that smaller nanocontact corresponds to wider frequency range.