Highly anisotropic magnetic domain wall behavior in-plane magnetic films

We have studied nucleation of magnetic domains and propagation of magnetic domain walls (DWs) induced by pulsed magnetic field in a ferromagnetic film with in-plane uniaxial anisotropy. Different from what have been seen up to now in out-of-plane anisotropy films, the nucleated domains have a rectangular shape in which a pair of the opposite sides are perfectly linear DWs, while the other pair present zigzags. This can be explained by magnetostatic optimization, knowing that the pulse field is applied parallel to the easy magnetization axis. The field induced propagation of these two DW types are very different. The linear ones follow a creep law identical to what is usually observed in out-of-plane films, when the velocity of zigzag DWs depends linearly on the applied field amplitude down to very low field. This most unusual feature can be explained by the shape of the DW, which makes it possible to go round the pinning defects. Thanks to that, it seems that propagation of zigzag walls agrees with the 1D model, and these results provide a first experimental evidence of the 1D model relevance in two dimensional ferromagnetic thin films. Let's note that it is the effective DW width parallel to DW propagation direction that matters in the 1D model formula, which is a relevant change when dealing with zigzag DWs.