Eigenfrequencies of vortex state excitations in magnetic submicron-size disks

Abstract

We have theoretically and numerically studied the dynamic properties of the vortex magnetic state in soft submicron ferromagnetic dots with variable thickness and diameter. To describe the vortex translation mode eigenfrequencies, we applied the equation of motion for the vortex collective coordinates. We calculated the vortex restoring force with an explicit account of the magnetostatic interaction on the bases of the “rigid” vortex and two-vortices “side charges free” models. The latter model well explains the results of our micromagnetic numerical calculations. The translation mode eigenfrequency is inversely proportional to the vortex static initial susceptibility and lies in GHz range for submicron in-plane dot sizes.