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

Abstract

The optical and magneto-optical properties of as-deposited and annealed ${\mathrm{Fe}}_{51}$ ${\mathrm{Pt}}_{49}$ films were investigated in the photon energy range 1.55–10.5 eV. The magneto-optical Kerr rotation (${\mathrm{\theta }}_{\mathrm{K}}$) 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 ${\mathrm{\theta }}_{\mathrm{K}}$ spectra showed a tendency that is essentially quite similar to that of bulk Fe. The Kerr ellipticity (${\mathrm{\eta }}_{\mathrm{K}}$) 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 (${\mathrm{\varepsilon }}_{\mathrm{XY}}^{\prime }$) of both films at ∼4.8 eV are almost the same as that of bulk Fe. This leads to the conclusion that the ${\mathrm{\theta }}_{\mathrm{K}}$ enhancement at 4.8 eV is mainly due to a decrease in ${\mathrm{\varepsilon }}_{\mathrm{XX}}^{\mathrm{″}}$ and a peak shift in ${\mathrm{\varepsilon }}_{\mathrm{XY}}^{\prime }$ towards lower energy, but not to a plasma-resonance effect.