Monolayer-like lattice dynamics in bulk WSe2

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.