Exact and model operators for magnon–phonon interactions in antiferromagnets

A theoretical study is given of magnon–phonon interactions in antiferromagnetic materials. The roles of magnons and phonons as heat carriers and as sources of thermal resistance have been taken into consideration. The exact collision operator which represents the magnon–phonon interactions involved in the transport Boltzmann equations has been replaced by a model operator which possesses the same important properties. The effect of other scattering processes that either phonons or magnons are involved has also been investigated. A new expression for the thermal conductivity has been derived. It includes terms which represent both Normal and Umklapp magnon–phonon processes. The results obtained by using the new expression agree quantitatively with the experimental measurements on Fe Cl2

Research Highlights
► The magnon-phonon interactions in antiferromagnets have been investigated.
► The important properties of the associated exact collision operator have been studied.
► A model operator has been formulated that possesses the same properties.
► A new expression for the thermal conductivity has been derived.
► The results showed a good quantitative agreement with the experimental data of FeCl2.