2023/12/13 by Chaudhuri, Saumen, Bhattacharya, Amrita, Das, A. K. +2 · 4 citations
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci)
paper · doi:10.48550/arxiv.2312.08219
In the calculations of lattice thermal conductivity (κL), vital contributions stemming from four-phonon scattering are often neglected. The significance of four-phonon scattering in the thermal transport properties of monolayer (ML) MoS2 has been unraveled using first-principles calculations combined with the Boltzmann transport equation. If only three-phonon scattering processes are considered then the κL is found to be significantly overestimated (∼ 115.8 Wm-1K-1 at 300 K). With the incorporation of the four-phonon scattering processes, the κL reduces to 24.6 Wm-1K-1, which is found to be closer to the experimentally measured κL of 34.5 Wm-1K-1. Four-phonon scattering significantly impacts the carrier lifetime (τ) of the low-energy out-of-plane acoustic mode (ZA) phonons and thereby, suppresses its contribution in κL from 64% (for three-phonon scattering) to 16% (for both three- and four-phonon scatterings). The unusually high four-phonon scattering rate (τ4-1) of the ZA phonons is found to result from the simultaneous effect of the acoustic-optical frequency gap, strong anharmonicity, and the reflection symmetry imposed selection rule. The strong coupling between the quadratic dispersion of the ZA mode and the τ4-1 is discovered by the application of mechanical strain. The strain induced increase in the linearity of the ZA mode dispersion dramatically reduces the significance of the four-phonon scattering in the strained ML-MoS2, both qualitatively and quantitatively. These conclusions will provide significant insights into the thermal transport phenomena in ML-MoS2, as well as any other 2D material.