Journal ArticleRotational and dilational reconstruction in transition metal dichalcogenide moiré bilayersVan Winkle, Madeline; Craig, Isaac M.; Carr, Stephen; Dandu, Medha; Bustillo, Karen C.; Ciston, Jim; Ophus, Colin; Taniguchi, Takashi; Watanabe, Kenji; Raja, Archana; Griffin, Sinéad M.; Bediako, D. Kwabena<title>Abstract</title> <p>Lattice reconstruction and corresponding strain accumulation plays a key role in defining the electronic structure of two-dimensional moiré superlattices, including those of transition metal dichalcogenides (TMDs). Imaging of TMD moirés has so far provided a qualitative understanding of this relaxation process in terms of interlayer stacking energy, while models of the underlying deformation mechanisms have relied on simulations. Here, we use interferometric four-dimensional scanning transmission electron microscopy to quantitatively map the mechanical deformations through which reconstruction occurs in small-angle twisted bilayer MoS₂and WSe₂/MoS₂heterobilayers. We provide direct evidence that local rotations govern relaxation for twisted homobilayers, while local dilations are prominent in heterobilayers possessing a sufficiently large lattice mismatch. Encapsulation of the moiré layers in hBN further localizes and enhances these in-plane reconstruction pathways by suppressing out-of-plane corrugation. We also find that extrinsic uniaxial heterostrain, which introduces a lattice constant difference in twisted homobilayers, leads to accumulation and redistribution of reconstruction strain, demonstrating another route to modify the moiré potential.</p>Nature Publishing Group2023-12-0110494123Nature Communications1412041-1723https://doi.org/10.1038/s41467-023-38504-72238196National Science Foundation