Anomalous layer thickness dependent thermal conductivity of Td-WTe2 through first-principles calculation

摘要

The thickness dependent in-plane thermal conductivity of layered Tungsten ditelluride (WTe2) is investigated by first-principles calculation. With the layer number increasing from one to infinite, the thermal conductivity displays a decrease to increase trend. The underlying mechanism is attributed to the change of the phonon dispersion relations. As the layer number increases, optical phonon branches shift downward, which provide more channels for the Umklapp scattering, and result in the decrease of the thermal conductivity. Furthering increasing the layer number makes those low-frequency optical phonon branches having high group velocity and leads to the increase of the lattice thermal conductivity. (C) 2020 Elsevier B.V. All rights reserved.