Phonons in MoSe2/WSe2 van der Waals heterobilayer

TL;DR

This paper uses first-principles calculations to explore the vibrational properties of MoSe2/WSe2 heterobilayers, revealing unique phonon modes influenced by van der Waals interactions that affect thermal behavior.

Contribution

It provides new insights into the phonon characteristics of MoSe2/WSe2 heterobilayers, highlighting modes absent in individual monolayers and their dependence on weak vdW forces.

Findings

Presence of shear and breathing phonon modes unique to heterobilayers

Flexural mode deviations from monolayer behavior

Strong influence of vdW forces on phonon properties

Abstract

We report first-principles calculations of the structural and vibrational properties of the synthesized two-dimensional van der Waals heterostructures formed by single-layers dichalcogenides MoSe2 and WSe2. We show that, when combining these systems in a periodic two-dimensional 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 peculiar modes depend strongly on the weak vdW forces and has a great contibution to the thermal properties of the layered materials. Besides these features, the departure of flexural modes of heterobilayer from the ones of its monolayer parents are also found.