Influence of antiferromagnetic spin ordering on the far-infrared active optical phonon modes of alpha-MnSe

The effects of spin-phonon interaction and magnetic anisotropy on the temperature dependence of the infrared optical phonon modes in the antiferromagnetic alpha-MnSe are investigated by use of Green’s function formalism within 1/z perturbation framework. The renormalization effects are calculated explicitly as a function of temperature, phonon-phonon, and spin-phonon interaction constants. Temperature dependence of the renormalized LO phonon frequencies of the F1u infrared active and combinational phonon modes are calculated and compared with experimental data. We have shown that the inclusion of anisotropy is necessary in order to get a good quantitative agreement with the experiment.