Brillouin spectroscopy of spin waves in sputtered CoPt alloy films and Co/Pt/Co multilayered films

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Abstract
Sputtered Co1−xPtx (x=0–0.14) alloy films have been studied by Brillouin scattering of spin waves and compared with results on Co/Pt/Co multilayered films. Brillouin spectra of the surface spin waves in the sputtered alloy films are remarkably broadened as an increase of the Pt content. The in-plane coercivity of the films also increases as the increase of the Pt content, which indicates larger and better oriented grains with proper separations that result from higher Pt content. The broadening of the spin-wave spectra is caused by the magnetic inhomogeneity due to the grains in the film. The exchange stiffness constant of the CoPt alloy films is determined from the magnetic field dependence of the frequency shifts of the surface and standing spin waves. To investigate the exchange interaction in the inhomogeneous alloy films, Co/Pt/Co multilayered films with the Pt interlayer of thickness of 0–40 Å have been fabricated as a model material. From the analysis of the frequency shifts of the spin waves, the exchange interaction between Co layers through the Pt interlayer is evaluated.