Collective hydrodynamic magnon transport study in magnetically ordered insulator based on Boltzmann approach

The magnon, an elementary excitation of an orderly magnetic system, has recently received a great deal of attention due to its excellent spin transmission properties. Many researchers have observed a strong correlation between magnon transport properties and temperature. Although existing theories already include the influence of temperature, they cannot clearly explain many phenomena. In this article, we introduce a new scattering process, inspired by the nature of the magnon itself and based on the Boltzmann method, which clearly impacts the transport properties of the magnon. This new scattering process is named Normal scattering, and makes the transport of the magnon exhibit a fluid-like property, which can be captured by a viscous fluid transport equation. The theoretical predictions are in good agreement with experimental results and the proportion of Normal scattering in the overall scattering changes with temperature, which convincingly explains the temperature dependence of magnon transport.