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An epitaxial SmNiO3 thin-film grown on an LaAlO3 (001) substrate using pulsed laser deposition is investigated with spherical-aberration corrected scanning transmission electron microscopy techniques, including high-angle annular dark field, X-ray energy dispersive, and electron energy-loss spectroscopy. High-density Ruddlesden–Popper (RP)-type faults, which generate two types of image contrast due to overlaps along the electron beam direction, are identified with the translational vector of 1/2a⟨111⟩c, corresponding to 1/2a⟨101⟩c displacement of Sm atoms when observed along the [010]c zone axis. These defects originate from Sm-rich non-stoichiometry within the SmNiO3, and their directions depend on the local stress states. Lattice distortion induced by the RP faults reduces the metal-to-insulator transition temperature to around 340 K. The effects of high-density RP faults on the lattice strain, domain size, and strong electronic-lattice correlations indicate that RP faults can provide extra freedom to tailor the physical properties of SmNiO3 thin films for potential electronic device applications. High-density Ruddlesden–Popper-type faults are revealed in an epitaxial SmNiO3 thin film grown on LaAlO3 (001) by pulsed laser deposition, originating from Sm-rich non-stoichiometry, and their directions depend on the local stress states. Lattice distortion induced by the RP faults reduces the metal-to-insulator transition temperature to around 340 K. RP faults provide extra freedom to tailor intriguing properties of SmNiO3 for potential electronic device applications.

Epitaxial growth is of significant importance over the past decades, given it has been the key process of modern technology for delivering high-quality thin films. For conventional heteroepitaxy, the selection of proper single crystal substrates not only facilitates the integration of different materials but also fulfills interface and strain engineering upon a wide spectrum of functionalities. Nevertheless, the lattice structure, regularity and crystalline orientation are determined once a specific substrate is chosen. Here, we reveal the growth of twisted oxide lateral homostructure with controllable in-plane conjunctions. The twisted lateral homostructures with atomically sharp interfaces can be composed of epitaxial “blocks” with different crystalline orientations, ferroic orders and phases. We further demonstrate that this approach is universal for fabricating various complex systems, in which the unconventional physical properties can be artificially manipulated. Our results establish an efficient pathway towards twisted lateral homostructures, adding additional degrees of freedom to design epitaxial films.