Sweep rate-dependent magnetization reversal in epitaxial Fe/GaAs(001) and Fe/InAs(001) thin films

We present the magnetization reversal dynamics of epitaxial Fe thin films g rown on GaAs(001) and InAs(001) studied as a function of field sweep rate i n the range 0.01-160 kOe/s using magneto-optic Kerr effect. For 55 and 250 Angstrom Fe/GaAs(001), we find that the hysteresis loop area A follows the scaling relation A proportional to H-alpha with alpha=0.03-0.05 at low swee p rates and 0.33-0.40 at high sweep rates. For the 150 Angstrom Fe/InAs(001 ) film, alpha is found to be similar to 0.02 at low sweep rates and similar to 0.17 at high sweep rates. The differing values of alpha are attributed to a change of the magnetization reversal process with increasing sweep rat e. (C) 2000 American Institute of Physics. [S0021-8979(00)48608-1].