Polyhedron and Charge Ordering in Interfacial Reconstruction of a Hexagonal Ferrite/Sapphire Heterostructure

Interfacial reconstruction, emanating from the symmetry breaking at the interface, plays a key role in modulating the microstructures and properties of heterostructures. The appeal of revealing such a reconstruction resides in the underlying mechanism connected to the function of heterostructures and new insights into designing a new interface device. Here, we demonstrate an interfacial reconstruction in a large lattice-mismatch system, h-LuFeO₃/α-Al₂O₃ heterostructure. Combining the atomic-resolution imaging and spectroscopy of scanning transmission electron microscopy, the periodic variation of FeO immediate coordination and charge ordering of iron are revealed, indicating a strong lattice-charge coupling in the reconstruction. Such a reconstruction reported here suggests that polyhedral and electronic flexibility is important for the reconstruction formation and presents possibilities for further construction of more functional heterostructures.