We present an experimental study of ultrafast optical excitation of magnetostatic surface spin
wave (MSSW) packets and their spectral properties in thin films of pure iron. As the packets
leave the excitation area and propagate in space, their spectra evolve non-trivially.
Particularly, low or high frequency components are suppressed at the border of the
excitation area depending on the orientation of the external magnetic field with respect to the
magnetocrystalline anisotropy axes of the film. The effect is ascribed to the ultrafast local …