Interactions of spin waves with a magnetic vortex
  We have investigated azimuthal spin-wave modes in magnetic vortex structures using time-resolved Kerr microscopy. Spatially resolved phase and amplitude spectra of ferromagnetic disks with diameters from 5 $\mu$m down to 500 nm reveal that the lowest order azimuthal spin wave mode splits into a doublet as the disk size decreases. We demonstrate that the splitting is due to the coupling between spin waves and the gyrotropic motion of the vortex core. 
J. P. Park and P. A. Crowell