Light scattering by itinerant spin-density excitation in metals

Light scattering in metals in the presence of a static spin-density wave is considered. The cross section corresponding to excitation of a electron-hole pair with opposite spin is calculated. It has a threshold of 2g, where 2g is the spin-flip excitation gap. For Cr, the cross section is estimated to be comparable with the cross section for Raman scattering by optical phonons in metals and could be observable.