Brillouin light scattering on cobalt-chromium films

Brillouin light scattering has been used to observe high frequency thermal magnetic excitations in ion-beam sputtered Co-Cr thin films. The measurements were performed on 82 at. % Co samples, 100 Å, 350 Å and 750 Å in thickness, sputtered on single crystal Si substrates. The Brillouin scattering signals from these Co-Cr films were quite strong. All spectra show scattering due to surface magnons propagating in the film plane. Scattering due to bulk spin waves was found for the two thicker films. From the measured magnon dispersion for the surface mode, Damon-Eshbach theory was used to calculate the magnetization, the perpendicular anisotropy field and the gyromagnetic ratio for the films. The spin wave stiffness parameter was determined from the bulk magnon dispersion. These magnetic parameters are in reasonable agreement with results from ferromagnetic resonance.