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 Fe₅₁{Pt}₄₉$ films were investigated in the photon energy range 1.55--10.5 eV. The magneto-optical Kerr rotation (${{{θ}}}K$) 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 around 4.8 and 7.8 eV, respectively. The ${{{θ}}}K$ spectra showed a tendency that is essentially quite similar to that of bulk Fe. The Kerr ellipticity (${{{η}}}K$) 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 (εXY^') of both films at {~}4.8 eV are almost the same as that of bulk Fe. This leads to the conclusion that the θK enhancement at 4.8 eV is mainly due to a decrease in εXX^'' and a peak shift in εXY^' towards lower energy, but not to a plasma-resonance effect.