Optical and magnetooptical characterization of FeNi/Cu multilayers

A series of [FeNi(1.7 nm)/Cu(tCu)]30/Fe(10 nm) multilayers with the range of tCu from 0.36nm to 4.32nm deposited on glass substrates was studied by measuring the effective optical constants n and k, saturation magnetooptical polar Kerr rotation θ k and ellipticity ηk and evaluating the effective complex off-diagonal elements of the dielectric tensor e xy ′ and e xy ″ . It was found that the four primary quantities e xy ′ , e xy ″ , n and k vary concurrently with respect to tCu, while the dependences of θ k and η k on tCu differ drastically. To explain this difference the contributions of both the real and imaginary parts of the off- diagonal dielectric tensor elements and the effect of complex optical constants have to be considered. No obvious correlation was found between the variation of n, e~ xy and the oscillations of GMR of the multilayers.