Search

The magnon, an elementary excitation of an orderly magnetic system, is currently receiving substantial attention due to its excellent spin transmission properties. Researchers have observed a clear correlation between magnon transport properties and temperature. Existing theories do include the influence of temperature, but cannot clearly explain many phenomena, including a detected abnormal negative signal. In this article, we build a new magnon transport theory based on the Boltzmann method, which incorporates a magnetic field-induced "anti-diffusion" driving term, a magnon-phonon interaction induced thermal driving term, and diverse scattering terms, such as a scattering process which leads magnons to a special state with a collective velocity. We claim that collective velocity is the crucial factor in producing an abnormally negative signal. We formulated an equation capturing the system's spin properties, which we solved. Our results qualitatively explain the abnormal phenomenon observed in experiments. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]