Raman scattering by spin excitations in α-MnSe

Raman spectra of polycrystalline α-MnSe were measured in the temperature range from 17 to 100 K. We found a peak at 18 cm^-1 at low temperatures that shifts to lower frequencies when the temperature increases. From frequency vs temperature dependence we assigned it as one magnon mode at k=0. The magnon dispersion relations were calculated using random phase Green function approximation. The exchange energies were estimated. The N\'eel temperature was determined by fitting the ω1M(T)/ω1M(0)=f(T/TN) dependence with the experimental data.