Corrugation-type instability of the free motion of 180° domain walls in uniaxial ferromagnets

Investigation of the spectrum of oscillations of a 180° domain wall (DW) freely moving in a uniaxial ferromagnet shows that the one-dimensional structure becomes unstable with respect to surface distortions in the region of negative effective mass (negative differential mobility). The upper critical value of the perturbation wave vector, above which the DW corrugation is not developed and the wave vector of a perturbation mode with the maximum increment are determined.