Phonons in WSe<sub>2</sub>/MoSe<sub>2</sub> van der Waals Heterobilayers
F. Mahrouche, Karim Rezouali, Sofiane Mahtout, Foudil Zaabar, Alejandro Molina‐Sánchez
Abstract
The first‐principles calculations of the structural and vibrational properties of the synthesized 2D van der Waals (vdW) heterobilayers (HBLs) formed by single‐layer dichalcogenides MoSe 2 and WSe 2 are reported. When combining these systems in periodic 2D heterostructures, the intrinsic phonon characteristics of the free‐standing constituents are to a large extent preserved but, furthermore, exhibit shear and breathing phonon modes that are not present in the individual building blocks. These unusual modes, which are extremely sensitive to weak vdW forces, could be a useful tool for the characterization of the optical properties of vdW heterostructures. In addition to these features, the departure of flexural modes of the HBL from the ones of its monolayer parents is also found.