Frequency-dependent dynamics of domain walls in yttrium iron garnet

An analysis of the frequency-dependent dynamics of domain walls in polycrystalline yttrium iron garnet samples is presented. This analysis has been carried out, on the one hand, considering the theoretical aspects related to the numerical solving of the motion of a Bloch wall using harmonic fields. On the other hand, we have measured the magnetic aftereffect phenomena by using the technique known as magnetic disaccommodation. The experimental results change drastically with the measuring frequency for all the samples, showing the presence of a relaxing process related to the electronic hopping between ferric and ferrous ions and magnetic accommodation processes. The agreement between these results and the theoretical model analyzed has led us to interpret these phenomena in terms of a time-dependent resonance mechanism when an induced anisotropy relaxing process takes place.