Monte Carlo simulation of the field sweep rate dependence of the coercivity in a micromagnetic model

We discuss, in the framework of a micromagnetic simulation, the relaxation properties of a hard magnetic system with distributed easy axis directions. The considered relaxation phenomenology was the field sweep rate dependence of the coercivity. From the results of our simulations, and following the conventional procedure, we have evaluated the 1D equivalent of the activation volume. The value we found for this parameter is in good agreement with the field average of the results obtained in a previous study, carried out in the same model system, on the time evolution (under constant applied demagnetizing field) of the magnetization. Finally, and from the direct examination of the configuration of the system during relaxation, we conclude that the activation volume value we obtained from the field sweep rate simulations measures, in units of the exchange correlation length, the average number of partly reversed nuclei that are formed due to thermal activation per unit of magnetization decrement