Brillouin light scattering study of exchange-coupled Fe/Co magnetic multilayers

A combined experimental and theoretical Brillouin light scattering study of thermally excited spin waves in Fe/Co multilayers with three and five magnetic layers in direct contact is presented. A large number of discrete, well-resolved peaks, classified as either surface or bulk standing modes of the stack, appear in the measured spectra. The investigation of their frequency dependence on the magnetic field intensity and incidence angle of light allowed us to determine the complete set of magnetic parameters of the multilayer. The interlayer exchange coupling and perpendicular interface anisotropy are discussed in detail. The profiles of the dynamic magnetization associated with different spin wave modes are calculated and utilized for the calculation of the Brillouin scattering cross section. The result, compared with experimental spectra, allowed the determination of the ratio between the magneto-optic constants of Fe and Co.