Static and dynamical study of the passage of a 180 degrees domain wall over an artificial energy barrier

The passage of a 180 degrees domain wall (DW) from a 1000 Angstrom thick uniaxial GdFe amorphous layer to a 500 Angstrom layer through a thin TbFe layer is presented. In this system, the TbFe layer acts as a potential energy barrier for the DW. The propagation field H-p at which the DW crosses the barrier is shown to increase linearly when the temperature is decreased. This is consistent with models based on crossing of the barrier by thermal activation. At very low (<0.5 K) temperature some deviations occur.