  Excitation of spin wave modes of a vortex-state magnetic dot by an
out-of-plane oscillating magnetic field is studied numerically in the presence
of a static in-plane magnetic field. It is shown, that the application of the
in-plane static field shifts the position of the vortex core and leads to the
separate excitation of different azimuthal dipolar spin waves my perpendicular
oscillating field. It is also shown that the excited dipolar azimuthal spin
waves excite the gyrotropic mode of the vortex core rotation and, depending on
the excitation frequency, cause a significant modification (increase or
decrease) of the apparent dissipation rate of the gyrotropic mode. The last
effect can be explained by the nonlinear parametric interaction between the
gyrotropic mode and the dipolar spin wave modes with different azimuthal
indices.
