DYNAMICAL PROPERTIES OF MAGNETIZATION REVERSAL IN AN ULTRATHIN AU CO FILM/

We present a dynamical study of hysteresis loops of a MoS2/[Au/Co/Au] sandwich performed by surface magneto-optical Kerr effect with a field variation rate up to 1.2 MOe/s. An interpretation of dynamical effect s at room temperature is proposed, using a modelization of the magneti zation reversal. We discuss simulations which describe two different p rocesses of the magnetization reversal to interpret the evolution of t he hysteresis loops for several rates of variation of the magnetic fie ld. For a first range of field variation rates lower than 180 kOe/s, t he predominant mechanism seems to be wall motion and beyond 180 kOe/s, an expression for the magnetization is given, which supposes micro-do mains reversal as a prevailing process. Finally, the general behaviour of the relaxation time, depending on the magnetic field, is investiga ted.