Multichannel thermal transport in crystalline Tl3VSe4

The validity of the particlelike phonon picture in describing the thermal transport physics in strongly anharmonic crystalline materials is a subject of recent debate. On the one hand, the Peierls-Boltzmann transport equation-based particlelike treatment of phonons was found to be insufficient in explaining the experimentally observed ultralow thermal conductivity of Tl3VSe4, and subsequently another thermal transport theory based on an additional thermal transport channel was proposed. On the other hand, the validity of this multichannel transport was questioned through a higher-level theory accounting for higher-order terms. Here, using the highest level of thermal transport theory with contributions from a temperature-dependent potential energy surface, lattice thermal expansion, force constant renormalization, long-range Coulombic interactions, and higher-order quartic phonon scattering processes, the validity of multichannel thermal transport is tested for Tl3VSe4. The particlelike transport channel is found to severely underpredict the experimentally measured thermal conductivity by a factor of 3 at a temperature of 300 K. The contribution of the wavelike coherent transport channel is found to be twice that of the particlelike channel, and the total thermal conductivity from multichannel transport theory is found to be in agreement with experimental measurements.