Study of the Kerr effect of CoxAg100-x granular films

A series of CoxAg100-x granular films was annealed at 100, 250, 400, and 50 0 degrees C, respectively. Both the dielectric function and polar Kerr effe ct were measured using a spectroscopic ellipsometer and a magneto-optical K err spectrometer in the 1.5-4.5 eV photon energy range. It was found that t he Kerr effect was greatly enhanced with increasing annealing temperature, especially for those samples having low Co compositions. After annealing, t he strong resonance peaks appear in the 3.7-4.1 eV range. For the typical s ample with x = 6, the maximum Kerr rotation angle is about 0.26 degrees nea r 4.0 eV after annealing at 500 degrees C. Through data analysis, the large negative peak at about 3.85 eV is attributed to the plasma edge of Ag, and the positive peak near 4.0 eV is attributed to the new magneto-optical str ucture and the properties of the granular film. The larger short-wavelength Kerr effect will be useful for increasing magneto-optical data-storage den sity. (C) 1999 American Institute of Physics. [S0021-8979(99)29408-X].