EVIDENCES OF NON-ARRHENIUS MAGNETIC-RELAXATION IN MACROSCOPIC SYSTEMS- EXPERIMENTS AND RELATED SIMULATIONS

We report on the time evolution of the magnetization measured under co nstant applied field in highly homogeneous amorphous CoZrDy thin films . Our results show that the thermally activated reversal proceeds afte r a time interval (waiting time) whose magnitude depends on the field value and during which the macroscopic state of the sample evolves ver y slowly. Also, and differently from the relaxation of systems having distributed properties, the observed reversal is accomplished in a fin ite time interval. The experimental data are adequately reproduced by the relaxation of a 2D micromagnetic model which clearly suggests that the thermally activated reversal takes place through a nucleation-pro pagation sequence also showing some indications of collective behavior .