INVESTIGATION OF THE DEPENDENCE OF BLS FREQUENCIES ON ANGLE OF INCIDENCE FOR THIN IRON FILMS

Brillouin light-scattering experiments have been done at various angle s of incidence, theta, for four specimens prepared by molecular-beam e pitaxy. The specimens were single ultrathin films of Fe deposited on s ingle-crystal Ag substrates. Dependence of magnon frequency on theta i s easily resolvable in all specimens. We find that the magnitude of th is dependence is in good agreement with a theoretical calculation that takes into account magnetic anisotropies, dipole-dipole, and exchange interactions. Our results imply that magnetic excitations in these sp ecimens are correlated over distances of at least 5000 angstrom.