  The dynamics of individual magnetic skyrmions confined in ultrathin film dots
is studied theoretically. The systems considered are transition metal
ferromagnets possessing perpendicular magnetic anisotropy and particular
attention is given to the dynamic response of the skyrmions to perpendicular
driving fields. By using micromagnetics simulations, it is shown that breathing
modes can hybridize with geometrically-quantized spin wave eigenmodes of the
circular dots considered, leading to distinct features in the power spectrum
that differ to the behavior expected for uniformly magnetized systems. The
field dependence of the breathing modes offers a direct means of detecting and
characterizing such skyrmion states in experiment.
