Magneto-Optical Kerr Effects of Nd-(Fe, Co) Thin Films

The contribution of Nd to the magneto-optical properties of vacuum-evaporated Nd-(Fe, Co) films has been investigated by measuring the wavelength dependence (for ¿=250 to 800 nm) of the Kerr rotation (¿K), together with the spectra of photoelectrons emitted under X-ray irradiation (XPS). The Kerr rotation in Nd-Co films increases with decreasing ¿ when the Nd concentration is over 14 at%, and shows peaks at 300 nm; while the Kerr spectra of Nd-Fe films levels off with increasing Nd content. The compositional dependence of the Kerr spectra of Nd-Co and Nd-Fe films is characterized by two factors: 1) the contribution of Nd to ¿K at short wavelengths, and 2) the differences in the Kerr spectra of crystalline and amorphous states of Co and Fe. The XPS intensity for Nd-Co and Nd-Fe is maximum at about 4.2 eV below the Fermi level, which corresponds to the peak in the ¿K spectra at 300 nm. In pseudobinary system Nd-(Fe,Co) films, ¿K is larger, over the entire range of wavelengths considered, than any other binary system with the same Nd composition; and Nd22 (Fe65 Co35)78 exhibits a ¿K of about 0.58° at 300 nm.