Four-phonon scattering and thermal transport in 2H–MoTe2

Among two-dimensional (2D) transition metal dichalcogenides, molybdenum ditelluride (MoTe2) is of great interest to achieving unique functionalities in diverse electronic, photonic, and phononic devices. Despite extensive studies over the past decade, the thermal transport properties and mechanisms of MoTe2 remain largely unclear. Here, we grow few-layer (7 L, 10 L, and 17 L) single-crystalline 2H–MoTe2 and measure their in-plane thermal conductivities using an optothermal Raman technique. The room-temperature values range from 4 to 9 W m−1 K−1, substantially lower than theoretical predictions considering only three-phonon scattering. By employing first-principles calculations and machine learning-assisted molecular dynamics simulations, we reveal that four-phonon scattering could suppress the thermal conductivity of 2H–MoTe2 by 80 %, which agrees with experimental measurement and is mainly attributed to the flexural acoustic modes. Thickness-dependent suppression is observed owing to the varying reflection symmetry. Our work highlights higher-order phonon-phonon interactions in 2D materials and offers guidance for the thermal design of emerging devices.