Simulated spin wave resonance (SWR) lines on magnetic thin films have been studied by using a surface anisotropy field together with a surface inhomogeneity model for magnetization near the film surface. Landau-Lifshitz dynamic equations of motion of magnetization with Bloch-type damping have been used in order to obtain absorption lines as function of a steady magnetic field applied along a general direction with respect to the film surface. It has been found that the line shape, the resonance field values and especially the peak intensities for higher order spin wave modes strictly depend on the surface parameter. As the applied field direction is varied from perpendicular to parallel to the film plane, surface spin wave modes appear (or disappear) depending on easy (or hard) plane uniaxial surface anisotropy. The line width changes with field direction and has its maximum value at the angle corresponding to a rapid change of resonance fields, even for a constant intrinsic relaxation parameter used in the calculations. This anomalous broadening arises from a relatively slower increase of the effective internal resonance field due to dynamic response of steady magnetization to the increase of the applied fields during the resonance for any particular mode at these intermediate angles. Using this simulation, SWR spectra of a NiMn film on quartz substrate has been analyzed. The spectra comprise two surface modes in addition to the bulk modes when the angle between applied field and film normal is smaller than 45 degrees. From the angular variation of the SWR spectra, it :is concluded that the surface spin pinning is mainly caused by an easy-plane uniaxial surface anisotropy field rather than surface inhomogeneity of the magnetization. * Corresponding author.
tions [8,9] showing also the possibility of obtaining the exchange integral which is an important parameter in a magnetic body. In fact, the feasibility of multi-peak ferromagnetic resonance observation was under consideration long before the relevant experiments were actually carried out. The first to describe it as 'spin wave resonance' was, as far as we know, Rado [1,2]. The