Revealing the Emergence of Moiré Pattern and the Dynamics in Layered Superlattices at the Nanoscale

Moiré patterns from misaligned periodic structures can bring merit to not only artistic designs but to material properties, a salient example being magic angle graphene where superconducting phase can be observed. Here, with liquid-phase transmission electron microscope (TEM), we construct superlattices with nanoparticles and observe for the first time Moiré pattern formation at the nanoscale in real time and space. To be specific, we observed layers of hexagonal lattices assembled from individual gold nanoparticles and control the nanoparticle shape to manipulate the interlayer and intralayer interactions, which leads to different Moiré patterns. We apply neural network-based machine learning to study the structures and single particle dynamics with high spatiotemporal resolution, which further helps to reveal the interplay between the Moiré pattern and the grain boundary evolution. Furthermore, calculations based on Lennard-Jones potential show distinct local position adjustment in different Moiré patterns both in plane and out of plan, resulting in normal, reduced order and disordered Moiré patterns. This work provides better understandings on nanoscale interactions which can serve as a guideline for bottom-up material design and helps to study related optical properties.