MAGNETOOPTICAL KERR SPECTRA OF ULTRATHIN CO FILMS

Magneto-optical Kerr loops and their energy spectra have been measured for ultrathin Co films sandwiched between Au layers. Polar Kerr hysteresis loops were detected for Co layer thicknesses down to 3 angstrom, showing complete squareness between 5 angstrom and 8 angstrom. When the Co layer is thicker than 20 angstrom, the spectral shape of the Kerr rotation, as well as the Kerr ellipticity, in an energy range of 1.5 approximately 5 eV agrees well with those calculated from bulk data. With decreasing Co thickness below 10 angstrom, the spectra become gradually smaller in magnitude than and different in shape from calculated ones.