Raman Scattering By Spin Excitations In Alpha-Mnse

Raman spectra of polycrystalline alpha-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 Neel temperature was determined by fitting the omega(1M)(T)/omega(1M)(0)=f(T/T-N) dependence with the experimental data.