Magnetization reversal dynamics in ultrathin magnetic layers

We propose an analytical expression of the magnetization reversal in ultrathin magnetic layers, modeling the after effects, and taking into account both domain-wall motion and nucleation processes. We apply our modelization to quantify the dynamical properties of the magnetization of MoS₂/Au/Co/Au sandwiches; we define the Barkhausen volume, the wall velocity, and the nucleation rate depending on the applied magnetic field and the radius and the density of nuclei sites on the surface of the sample. Finally, we investigate an original behavior of the switch of the magnetization in high dynamic regime. An attempt is made to explain the divergence of the coercive field in large field variation rates (dH/dt), by introducing both the thermally activated and the viscous processes driving the wall motion. {} 1996 The American Physical Society.