Longitudinal magneto-thermal conductivity and magneto-Seebeck of itinerant antiferromagnetic BaMn$_2$Bi$_2$

Abstract

Thermal transport, generally mediated by the direct microscopic exchange of kinetic energy via lattice phonons, can also be modified by contributions from additional quasiparticles, such as electrons and magnons. However, a comprehensive understanding of the magnon influence has yet to be realized and remains an active research area. The most significant roadblock has been a lack of available materials in which these three quasiparticles can be clearly identified and quantitatively examined in order to provide an intrinsic understanding, not only of their independent contributions to thermal conductivity but also of the cross-correlated interactions among them. Itinerant antiferromagnetic (AFM) BaMn$_{2}$Bi$_{2}$ with PT symmetry exhibits Anderson metal-insulator localization, which can be tuned into the metallic regime via an applied magnetic field due to its unique electron-magnon interactions. We identify itinerant AFM BaMn$_{2}$Bi$_{2}$ as an ideal material for scientific investigations into how these quasiparticles participate in thermal conductivity. Here, we present the direct contribution of electrons, phonons, and magnons to thermal conductivity, as well as their interspecies interactions, supported by detailed analyses conducted in the framework of the Boltzmann transport formalism. The comparison of the magneto-thermal conductivity and magneto-electrical conductivity, as well as the magneto-Seebeck effect of itinerant antiferromagnetic BaMn$_{2}$Bi$_{2}$, gives unique insight into how magnons participate in longitudinal thermal-associated phenomena.