GROWTH AND MAGNETIC DYNAMIC SCALING OF ULTRATHIN FERROMAGNETIC-FILMS - FE/AU(001)

Dynamic responses of the magnetic hysteresis of a few monolayer thick smooth Fe films on a Au(001) surface were measured by the surface magneto-optic Kerr effect technique. The Fe films were prepared by molecular beam epitaxy technique and their growth and structures were characterized in situ by high resolution low energy electron diffraction with angular profile measurement. The shape of the hysteresis loop changes with the frequency OMEGA and the amplitude H0 of the applied periodic magnetic field. Over a range of frequency (<225 Hz) at a fixed amplitude and at room temperature, the area of the hysteresis loops follows a scaling form. The best fit of a scaling function to the frequency-dependent area gives exponents a = 0.58 +/-0.03 and b = 0.24 +/- 0.02. For low values of frequency (<25 Hz) and amplitude (<400 Oe), the area of hysteresis loops measured at room temperature reduces to a power law A is-proportional-to H-0alphaOMEGA(b) with a +/- 0.59 +/- 0.07 and b = 0.26 +/- 0.05. Our measured exponents and the scaling function are consistent with recent results of theory and Monte Carlo simulations.