Nonlinear dynamics of vortexlike domain walls in magnetic films with in-plane anisotropy

The nonlinear nonstationary dynamics of domain walls with variable two-dimensional internal structure (topological solitons with internal degrees of freedom) under the action of an external magnetic field was investigated in magnetic films having an in-plane anisotropy and a small damping coefficient alpha. The iteration calculation procedure of the temporal evolution of the magnetization distribution is based on the predictor-corrector method for direct numerical solution to the Landau-Lifshitz equations. The variable time step procedure was employed. It is shown that along with the periodic change of the internal structure of a wall occurring with a certain period T there also appear the subperiodic vibrations of some parts of the walls relative to the other parts which results in the high-frequency oscillations (similar or equal to 10(11) Hz) of the velocity of a domain wall in the fields above some critical field H-c at a small damping. The dependence of the period of dynamic rearrangement of the internal structure of the walls on the external magnetic field and damping was studied. The singular dependence of T on H is established to be different from the (H-2/H-c(2)-1)(-1/2) law which is typical of one-dimensional models of a wall. The dependence of H-c on zeta is evaluated and appears to differ substantially from that of the one-dimensional models.