Domain wall motion in permalloy nanowires

The wires are made of permalloy (Ni₈₀Fe₂₀ soft magnetic alloy, i.e. with very small anisotropy and magnetostriction), 5 nm thick and 200 nm wide. The domain wall at these sizes is of the transverse magnetization type. At time t=0 a field oriented along the wire is applied.
Color coding of the movies according to the in-plane component of the magnetization (circular color code). The movie shows a section of the wire, that is shifted periodically so as to always show the domain wall. See publication in Nature Mater. (2003) for more details.

perfect wire, 12 Oe field (2.5 MB): stationnary motion, in which the wall adopts a slightly distorted structure. In this case, this behaviour can be observed for fields between 0 and 14 Oe. The nanowire section is 1 micrometer long

perfect wire : 20 Oe field (12.2 MB): motion above the critical field (known as the Walker field), where the wall structure is periodically reversing through the injection and disparition of an antivortex (also known as a cross line). The nanowire section is 1 micrometer long.

rough wire, 20 Oe field (3.7 MB): motion for the same high field but in a rough wire (grain average size 10 nm). The roughness suppresses the injection of the antivortex, so that the wall keeps moving at a high velocity. This velocity is the same as the maximum velocity seen (at 14 Oe) for a perfect wire. The nanowire section shown is 2 micrometers long