Theory of inelastic light scattering of itinerant electron ferromagnets

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Abstract
Raman scattering in a reflection experiment is discussed. It is assumed that coupling to spin flip excitations occurs due to spin-orbit coupling, as in an insulator. Within the tight binding approximation, the polarization selection rules contain one term from single site processes which has the same form as in an insulator, and one from neighbouring site processes which may be different. If the first term is dominant, the vertex coupling the excitations to the incident and scattered light is only weakly momentum dependent and scattering by the stoner excitations is much weaker than magnon scattering. The magnon line is broadened because of the finite skin depth of light in the specimen; for nickel this broadening is greater than the intrinsic linewidth as observed in ferromagnetic resonance experiments.