Exploring van der Waals Heterostructures behavior: Stability vs. Twisting

While the outstanding properties of van der Waals 2D materials are widely known, recent efforts have been focusing on the physics emerging from the stacking and rotational degrees of freedom of these lamellar compounds. Notable examples are unconventional superconductivity in twisted bilayer graphene¹ and frictionless dynamics obtained by switching from commensurate to incommensurate orientation in graphitic systems².

In this study we focus on an often overlooked question: are twisted geometries thermodynamically stable and what defines the energy landscape induced by the rotation? We answer this question in the MoS₂/Graphene system, as the pristine components are widely known and experimental data on this heterostructure is contradictory.

We use a refined classical potential to simulate edge-free rotated heterostructure and obtain the energy behavior as a function of the imposed angle in the thermodynamic limit. Our work shows the breakdown of a known theory of 2D incommensurate interfaces³ and offers new insights about the microscopic mechanism governing the stability of this class of materials.

[1] Y. Cao et al., Nature 556, 43 (2018)
[2] M. Dienwiebel et al., Phys. Rev. Lett. 92, 126101 (2004)
[3] A. D. Novaco and J. P. McTague, Phys. Rev. Lett. 38, 1286 (1977)