Probing Thermomechanical Properties of Two-dimensional van der Waals Architectures Using Surface Acoustic Waves

Surface acoustic waves (SAWs) propagate along material surfaces or at solid-air, solid-liquid, solid-solid, and solid-vacuum interfaces. SAWs are confined to surfaces within the depth of one wavelength, and the SAW velocity depends on the elastic properties of the material. Hence SAWs can be used to determine thermomechanical properties like Young’s modulus and thermal conductivity of 2D materials. Inspired by a recent electron microscopy experiment [1], we use molecular dynamics (MD) simulations to investigate the effect of SAWs on the thermomechanical behavior of MoS₂ mono- and bilayers. The MD results for Young’s modulus and thermal conductivity of 2D MoS₂ are in excellent agreement with experiments and density functional theory calculations. We find nanopores have a dramatic effect on the thermal conductivity, which drops by an order of magnitude in a nanoporous MoS₂ monolayer. We also examine the effect of SAWs on Moiré patterns between 2D van der Waals materials.

[1] “Tailoring the Angular Mismatch in MoS₂ Homobilayers through Deformation Fields”, Burns et al., to be published.