Atomic structures of perovskite oxide moiré lattices

Epitaxial interfaces of two-dimensional (2D) complex oxide thin films have been fertile playgrounds for exploring electromagnetic phenomena driven by electron correlations. The recent development of freestanding oxide membranes provides opportunities for designing heterointerfaces beyond conventional thin film synthesis. By mechanically assembling individual oxide membranes into stacked heterostructures, one can create oxide interfaces free from epitaxial constraints, similar to 2D van der Waals heterostructures. In order to harness and predict new emerging properties from such non-epitaxial oxide interfaces, it is essential to understand their atomic structures. This presentation focuses on the atomic structures of twisted oxide membrane bilayers, which form the simplest moiré lattices based on perovskite oxide membranes. Advanced transmission electron microscopy and scanning transmission electron microscopy were leveraged to visualize atomic structures of the oxide moiré lattices. The presentation will also discuss how material processing and lattice dimensionality influence the structure of these twisted oxide bilayers.