On the two-magnon scattering of light and neutrons

The effect of magnon-magnon interaction on the two-magnon scattering of light and neutrons has been calculated at finite temperatures. Neglecting life-time effects the temperature dependence of the magnetization and that of the spin wave energy as well as the Bose functions for the magnon occupation number have been taken into account. In the low temperature region, where this spin wave approximation is valid, we have gotten a shift of the two-magnon peak toward smaller energies with increasing temperature, which scales with the temperature dependence of the magnon energy and a broadening of the peak as well. These features are in agreement with the result of optical experiments.