The effect of four-phonon interaction on phonon thermal conductivity of hexagonal VTe2 and puckered pentagonal VTe2.

Abstract

The traditional view is that complex structures have lower lattice thermal conductivity. However, it is observed that complex structures have higher lattice thermal conductivity than simple atomic structures in VTe2 systems after considering the four-phonon scattering effect. In this work, we calculate the lattice thermal conductivity of an H-VTe2 monolayer with a simple atomic structure and that of a PP-VTe2 monolayer with a complex atomic arrangement using first-principles calculations combined with the Boltzmann transport theory under the conditions of with and without the four-phonon scattering process. Our findings reveal that the lattice thermal conductivity of the PP-VTe2 monolayer along the x or y direction is 3-4 times lower than that of the H-VTe2 monolayer when only considering the three-phonon scattering process. After taking into account the four-phonon scattering process, the lattice thermal conductivity of both monolayers decreases. For the H-VTe2 monolayer, the lattice thermal conductivity decreases by 88.7% (from 1.33 to 0.15 W m-1 K-1) compared to only considering the three-phonon scattering process, mainly due to strong four-phonon scattering. In addition, the PP-VTe2 monolayer experiences a lower decrease in lattice thermal conductivity, with reductions of 12.5% (from 0.4 to 0.35 W m-1 K-1) and 11.7% (from 0.34 to 0.3 W m-1 K-1) in the x and y directions, respectively, because of the weak four-phonon scattering. Notably, the lattice thermal conductivity with the four-phonon scattering process of the H-VTe2 monolayer is twice as low as that of the PP-VTe2 monolayer. Hence, our findings suggest that even simple atomic structures can exhibit lower lattice thermal conductivity than complex structures when considering four-phonon interaction.