Magneto-optical properties of Fe-Pt alloy films in the range 1.55-10.5 eV

The optical and magneto-optical properties of as-deposited and annealed Fe sub 51 Pt sub 49 films were investigated in the photon energy range 1.55-10.5 eV. The magneto-optical Kerr rotation ( theta sub K ) spectra of both films were found to show a dispersion-type structure in the 4.6-7.8 eV region: they have large negative and broad positive peaks at approx 4.8 and 7.8 eV, respectively. The theta sub K spectra showed a tendency that is essentially quite similar to that of bulk iron. The Kerr ellipticity ( eta sub K ) spectra are bell shaped, exhibiting a large negative peak at 6.3 eV. Plasma edges were observed at 6.9 eV for the as-deposited film and at 7.3 eV for the annealed film. The absolute value of the real part of the off-diagonal dielectric element ( epsilon ' sub XY ) of both films at approx 4.8 eV are almost the same as that of bulk Fe. This leads to the conclusion that the theta sub K enhancement at 4.8 eV is mainly due to a decrease in epsilon " sub XX and a peak shift in epsilon ' sub XY toward lower energy, but not to a plasma-resonance effect.