Novel Magnon Transport Properties in Magnetic Oxides by Mesoscopic Boltzmann Approach

The coherent transport properties of magnon in ferromagnetic insulator(FI) demand precise physical understanding of magnon scattering and relaxation processes. In this presentation, we invent a general magnon Boltzmann equation from full quantum magnon Hamiltonian[1]. By including N-process magnon-scattering due to dipole-dipole interaction, we demonstrated a novel collective decay dynamics of magnon group, which showed hydrodynamics transport properties of magnon. To conduct N-process scattering, a new spatial dependent magnon interaction field λ was introduced, which was describing collective local field in magnon. We also found N-process scattering is the physical origin that why coherence magnons can transfer to thermal magnons in FI relaxation process. Furthermore, our results showed magnon current can be manipulated by varying of anisotropy in magnetic oxides, especially in strong anisotropic energy materials, such as NiFe2O4 or CoFe2O4. In this framework, we also provide the methods to manipulate magnon transport by applying gradient magnetic field and gradient T field.

[1] T. Liu, W. Wang & J. Zhang, PHYS. REV. B, 99, 214407 (2019).