Domain wall injection and propagation in planar Permalloy nanowires

We have used high-sensitivity magneto-optics to study the magnetic switching of a single 20 μm long, 100 nm wide, 5 nm thick planar Permalloy wire made by focused ion beam milling. It is found that the switching field of the wire can be dramatically reduced by the addition of a large end pad to the wire, which serves as a domain wall injector. We show that once injected, the domain wall is able to move very freely along the wire. No measurable pinning of the domain wall was observed at a shallow kink in the middle of the length of the wire. We thus show that such wires can be considered as domain wall conduits, with many applications in magnetoelectronic devices.