Dynamics of magnetostatic wave solitons in the vicinity of frequency cut-off

Abstract Nonlinear dynamics of one-dimensional pulses of exchangeless backward volume magnetostatic waves propagating in thin ferrite films with a thickness 2 l =(3–10) μm is studied numerically. The Whitham's approach of taking into account the exact wave dispersion is utilized. It has been found that in the case of small wave numbers (0.02 k 0 l ⩽0.05), even under a validity of quasi-stationary approximation, a commonly used polynomial approximation for the wave dispersion gives only rough description for nonlinear pulse dynamics. The reason is a presence of cut-off at higher frequencies. For greater wave numbers ( k 0 l ⩾0.1), the nonlinear wave dynamics coincides with results obtained earlier in the parabolic approximation for the wave dispersion. Two-dimensional dynamics of nonlinear pulses is also investigated briefly in the full dispersion approach. The collapse-like phenomena have been found there when the central wave number is chosen as k 0 l ⩾0.04.