Moiré-Engineered Oxide Membrane Heterostructures

Moiré interference between twisted complex oxides offers new prospects for fundamental research and the discovery of novel physical phenomena, such as 2D dipole crystals with moiré periodicity, non-collinear magnetism, coexisting moiré periodic antiferromagnetic and ferromagnetic order, and topological magnetic quasiparticles. We have fabricated twisted bilayers from freestanding SrTiO₃ membranes with precisely controlled twisting angles and adopted depth sectioning-based STEM methods to investigate lattice-electron correlations at the moiré interface. We provide theoretical and experimental evidence of periodically localized charge under the coincidence site lattice (CSL) condition, as well as directly coupled interfacial atomic geometries. These interfacial moiré charge localizations accompany the emergence of a localized flat-band structure that can drive new electronic phases. Our work gives novel insight into controlling periodicity in interfacial phenomena and opens pathways to discover moiré-lattice-driven charge-orbital correlations and their functionalities.

This work has been done in collaboration with Min-Su Kim, Kyoungjun Lee, Ryo Ishikawa, Kyung Song, Naafis Ahnaf Shahed, Ki-Tae Eom, Mark S. Rzchowski, Evgeny Y. Tsymbal, Teruyasu Mizoguchi, Si-Young Choi.