Dynamics of magnetization reversal in thin polycrystalline Ni80Fe20 films

The dynamic magnetization reversal behavior of polycrystalline Ni80Fe20 fil ms (thickness 60 and 200 Angstrom) was studied in the temperature range 90- 300 K by applying a magnetic field along the easy magnetization axis of the samples. The loop area A is found to follow the scaling relation A proport ional to H(o)(alpha)Omega(beta)T(-gamma) with alpha approximate to 0.9, bet a approximate to 0.8, and gamma = 0.38 for both thicknesses. This behavior is only qualitatively consistent with theoretical models if the magnetizati on reversal mechanism is identical for both films, independently of the app lied field and sample temperature. The observed scaling exponent values ind icate that domain nucleation and domain-wall motion process dominate the ma gnetization reversal process, which is not included in current theoretical models based on coherent rotation. Furthermore, the exponents alpha and bet a are found to be independent of the temperature, indicating that the dynam ic reversal mechanism is unchanged in this temperature range. [S0163-1829(9 9)06537-6].