Dynamics of domain walls in amorphous GdFe ultrathin films

The magnetization process of amorphous GdFe ultrathin films with perpendicular anisotropy occur by domains nucleation and domains wall (DW) motion. The DW motion is studied optically as a function of the applied field H at room temperature. It is found experimentally that the DW velocity can be expressed as V =C0 exp (H/H1) where H1 is a linear function of the nucleation field HN which depends on the nature of the alloy. The dependence of the DW velocity on the applied field is assumed to be related to the interaction of DW with pinning centers which can be overcome by thermal activation according to a model given by Riehmann and Nembach [J. Appl. Phys. 55, 1081 (1984)].