Study of optical and magneto-optical properties of CoFe-HfO₂ granular magnetic films

Granular films of composition (CoFe)_x(HfO₂)_1-x with continuous variation of the Co_0.5Fe_0.5 volume fraction in the range 0.1<x<0.9 have been prepared by e-beam co-evaporation. The optical properties of the thin granular composite films have been determined from transmission and reflection spectra in the 300-1100 nm region. The optical characteristics of the granular films as a function of x were also determined by the ellipsometrical method at λ = 632.8 nm. We find that the transmission and reflection spectra and the dielectrical function have anomalies near the percolation threshold at x_p≈0.45. The Faraday rotation in the films was determined at λ = 632.8 nm. The spectral dispersion of Faraday effects have peak in the region of the plasmon frequency. The Faraday effect is greatly enhanced near x_p. The calculated optical and magneto-optical parameters, described in the framework of the effective medium approximation, are in qualitative agreement with experimental data.