FePt thin .lms have been prepared at dierent substrate temperatures by DC magnetron
co-sputtering. The .lms change from a disordered fcc structure to a L10 fct structure with
temperature. The magnetic and the magneto-optical properties of those FePt ....
FePt thin .lms have been prepared at dierent substrate temperatures by DC magnetron
co-sputtering. The .lms change from a disordered fcc structure to a L10 fct structure with
temperature. The magnetic and the magneto-optical properties of those FePt .lms have been
studied. The dependence of spectral changes on the formation of a chemically-ordered L10structure
is observed in the polar magneto-optical Kerr rotation. In the spectra, the ultraviolet peak
located in the high-energy range (4.0 { 4.5 eV), which is related to electronic transitions on Pt
atomic sites, is observed for all samples. On the contrary, the peak related to transitions on Fe
atomic sites, which is located in the low-energy range (1.5 { 2.0 eV), is only observed for highly
chemically-ordered samples. Compared with the spectra for the L10 structure of FePt .lms pre-
pared by using molecular beam epitaxy, the infrared peak related to Fe sites is shifted to low energy.