Atomic Reconstruction in Trilayer Graphene Moiré Superlatices

Moiré superlattices formed from independently twisting trilayers of graphene have been proposed as an ideal model for studying electronic correlation. Multilayered moiré systems offer several advantages over their twisted bilayer analogs, including more robust and tunable superconductivity, a wide range of twist angles associated with flat band formation, and larger scale moiré patterns. Atomic reconstruction, which strongly impacts the electronic structure of twisted graphene structures, has been suggested to play a major role in the relative versatility of super-conductivity in trilayers. Despite this, reconstruction in graphene trilayers has been only probed using indirect measurements or those only applicable to exposed samples. Herein, we exploit an inteferometric 4D-STEM approach to obtain displacement and strain maps in a representative range of twisted trilayer graphene structures. This methodology correlates local intensity modulations to stacking order and allows us to selectively probe bilayer interfaces within the material. The resulting mechanism we present informs a more complete understanding of how atomic reconstruction scales with layer number in graphene moirés and modulates symmetries crucial for establishing superconductivity.