Strong anisotropic thermal conductivity of monolayer WTe 2

Tungsten ditelluride (WTe 2 ) has attracted increasing attention due to its large magnetoresistance and pressure-induced superconductivity. In this work, we investigate the thermal conductivity ( κ ) of monolayer WTe 2 by performing first-principles calculations, and find strong anisotropic κ with predicted room-temperature values of 9 and 20 W m –1 K −1 along two principal lattice directions, respectively. Such strong anisotropy suggests the importance of orientation when engineering thermal-related applications based on WTe 2 . The anisotropy of κ is attributed to the in-plane linear acoustic phonon branches, while the out-of-plane quadratic acoustic phonon branch is almost isotropic. The size dependence of κ shows that the size effect can persists up to 10 μ m, and the anisotropy decreases with decreasing sample size due to the suppression of low-frequency anisotropic phonons by boundary scattering.