Atom-by-atom imaging of moiré transformations in 2D transition metal dichalcogenides
Yichao Zhang, Ji‐Hwan Baek, Chia‐Hao Lee, Yeonjoon Jung, Seong Chul Hong, Gillian Nolan, Kenji Watanabe, Takashi Taniguchi, Gwan‐Hyoung Lee, Pinshane Y. Huang
Abstract
Understanding the atomic-scale mechanisms that govern the structure of interfaces is critical across materials systems but particularly so for two-dimensional (2D) moiré materials. Here, we image, atom-by-atom, the thermally induced structural evolution of twisted bilayer transition metal dichalcogenides using in situ transmission electron microscopy. We observe low-temperature, local conversion of moiré superlattice into nanoscale aligned domains. Unexpectedly, this process occurs by nucleating a new grain within one monolayer, whose crystal orientation is templated by the other. The aligned domains grow through collective rotation of moiré supercells and hopping of 5|7 defect pairs at moiré boundaries. This provides mechanistic insight into the atomic-scale interactions controlling moiré structures and illustrates the potential to pattern interfacial structure and properties of 2D materials at the nanoscale.