The apparatus for measurement of magnetooptical spectra using a polarization modulation technique has been improved to extend the short-wavelength limit to about 200 nm in the ultraviolet range. Short-wavelength characteristics of the light source, the focusing system including mirrors and lenses, the monochromator, the polarizer and the analyzer were improved. The techniques of calibration for Kerr rotation and ellipticity were also refined. With the use of the newly designed system, the magnetooptical Kerr rotation and Kerr ellipticity of FePt/Pt multilayers, as well as of FePt alloys of different compositions were evaluated for photon energies between 1.2 and 5.9 eV.

Magnetooptical (MO) spectra were measured between 1.2 and 5.9 eV in Pt/Co and Pt/Fe multilayers and corresponding Pt-Co and Pt-Fe alloys produced by DC magnetron sputtering. Real and imaginary parts of off-diagonal conductivity-tensor elements were calculated using optical constants n and k, deduced from the reflectivity spectra measured with synchrotron radiation. The off-diagonal conductivities thus obtained suggest that magnetooptical spectra of multilayers are caused by those of corresponding alloys formed at the interface. To confirm this assumption, a simulation of MO spectra was performed by means of the virtual optical constant method using diagonal and off-diagonal conductivity of the alloy layer determined by the experiment. The results of calculation provide evidence for the presence of an alloy layer at the interface between Pt and transition metal.

Superlattices consisting of Fe and Au ultrathin layers with thickness of a few monolayers were prepared. Fonnation of Llo-type structure in the Fe(lML)!Au(lML) superlattice was confinned by X-ray diffraction. Magneto-optical studies suggest fonnation of a new energy band structure characteristic of the new alloy.

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