Monolayer-like lattice dynamics in bulk WSe2

Abstract

Understanding the microscopic lattice dynamics is essential for regulating the thermal properties in two-dimensional layered materials. In transition metal dichalcogenides, the layered structures result in different but closely related phonon dispersions between monolayer and bulk. Here, by combining inelastic X-ray scattering and first-principles calculations, the lattice dynamics of tungsten diselenide (WSe2) was investigated comprehensively, and a monolayer-like lattice dynamics in the bulk WSe2 was revealed. We performed the first temperature-dependent phonon dispersions measurement and obtained the mode Grüneisen parameters of bulk WSe2, which are found to be in better agreement with the calculations on the monolayer system than those of the bulk. This observation indicates that lattice dynamics in bulk WSe2 hold the characteristic of monolayers. The result provides valuable insights into the thermal properties of WSe2-based devices.