DOMAIN-WALLS IN ULTRATHIN FERROMAGNETIC-FILMS - VELOCITY AND FRACTAL DIMENSION

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