EXCHANGE AND ANISOTROPY EFFECTS ON SPIN-WAVES IN EPITAXIAL CO FILMS

Using Brillouin scattering we have investigated the effect of large in -plane anisotropy on magnetic excitations in b axis-oriented epitaxial 50-nm Co films. For in-plane fields along the easy axis the magnon fr equencies increase monotonically with increasing field. For in-plane f ields along the hard axis, nonmonotonic behavior is observed in which the surface to bulk spin-wave character of one magnon mode changes as a function of applied field. Although fits to the data based on a full theoretical treatment are consistent with parameters in the literatur e and with parameters extracted from the magnetization data, we show t hat uncertainties in crystal orientation (as small as 1 degrees) can p roduce dramatic effects in the quantitative data interpretation.