Domain Walls in Ultrathin Ferromagnetic Films: Velocity and Fractal Dimension

Abstract
We report on the first measurements of the domain wall (DW) velocity at magnetization reversal as a function of the applied magnetic field in ultrathin ferromagnetic Au/Co/Au films with perpendicular anisotropy. The Barkhausen volumes as well as Gilbert damping parameters are derived. The limit of the DW velocity is reached in high field. The change in fractal dimension of the domain wall with field is correlated to the crossover between thermally activated and viscous processes driving the wall motion.