Degradation of domains with sequential field application

Recent experiments show striking unexpected features when alternating square magnetic field pulses are applied to ferromagnetic samples: domains show area reduction and domains walls change their roughness. We explain these phenomena with a simple scalar-field model, using a numerical protocol that mimics the experimental one. For a bubble and a stripe domain, we reproduce the experimental findings: the domains shrink by a combination of linear and exponential behavior. We also reproduce the roughness exponents found in the experiments. Our results suggest that the observed effects are due to a change in the disorder correlation length when the domain walls are subject to alternating fields during the first cycles, where the initial state of the interface plays a crucial role. Finally, our simulations explain the area loss by the interplay between disorder effects and effective fields induced by the local domain curvature.

Automated summary

The recent experiments demonstrate that alternating square magnetic field pulses applied to ferromagnetic samples result in a reduction in domain area and a change in domain walls roughness. This phenomenon is explained by a numerical protocol using a simple scalar-field model, which mimics the experimental findings. The observed effects are attributed to a change in disorder correlation length and the interplay between disorder effects and effective fields induced by local domain curvature.