Domain wall motion in nanowires

We investigated the motion of domain walls in ferromagnetic cylindrical nanowires by solving the Landau–Lifshitz–Gilbert equation numerically for a classical spin model in which energy contributions from exchange, crystalline anisotropy, dipole–dipole interactions, and a driving magnetic field are considered. Depending on the diameter, either transverse domain walls or vortex walls are found. A transverse domain wall is observed for diameters smaller than the exchange length of the given system. In this case, the system effectively behaves one dimensionally and the domain wall velocity agrees with the result of Slonczewski for one-dimensional walls. For larger diameters, a crossover to a vortex wall sets in which enhances the domain wall velocity drastically. For a vortex wall the domain wall velocity is described by the Walker formula.publishe