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arXiv · 2507.04082

Longitudinal magnon transport properties in the easy-axis XXZ Heisenberg ferromagnet on the face-centered cubic lattice

M. R. Parymuda
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Abstract

We present a detailed investigation of longitudinal magneto-thermal transport in the $S=1/2$ ferromagnetic XXZ model with easy-axis exchange anisotropy ($\Delta>1$) on a face-centered cubic lattice consisting of four sublattices. We employ linear spin-wave theory and the Kubo formalism to evaluate the longitudinal spin and thermal conductivities, both of which exhibit activated temperature dependence in the low-temperature regime, and to determine their magnetic-field dependence. Our analysis indicates that a magnon gap is crucial for ensuring the convergence of these conductivities. Furthermore, by examining the ratio of thermal conductivity to spin conductivity, we identify an analog of the Wiedemann-Franz law for magnon transport at low temperatures. Finally, we demonstrate that these results can be generalized to systems with arbitrary spin.

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M. R. Parymuda. 2025-07-05. Longitudinal magnon transport properties in the easy-axis XXZ Heisenberg ferromagnet on the face-centered cubic lattice. https://doi.org/10.1016/j.jmmm.2025.173608

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