DYNAMIC INSTABILITY AND MAGNETIC AFTER-EFFECT IN DOMAIN-WALL DYNAMICS

Nonlinear flexural and translational vibrations of a single polarized domain wall in yttrium-iron-garnet, generated by repetitive rf pulses of a driving magnetic field have been investigated by the inductive te chnique. The unstable growth of the wall vibration amplitude was obser ved in the real-time signal as well as in the amplitude-frequency curv es. This instability displays hysteresis with respect to the amplitude and frequency of the field and is dependent on the pulse period to pu lse duration ratio. It was directly proved that the observed nonlinear ities are determined by the interaction between the moving domain wall and the local potential well formed by dynamic defects responsible fo r the magnetic after-effect. A step change in the wall position caused by an additional dc field results in the step rise in the wall vibrat ion amplitude followed by a slow decay with the time constant approxim ately 50 ms. The spatial width of the potential well is also estimated experimentally to be less than the wall width (1 mum).