The oxide interfaces between materials with different structural symmetries have been actively studied due to their novel physical properties. However, the investigation of intriguing interfacial phenomena caused by the oxygen octahedral tilt (OOT) proximity effect has not been fully exploited, as there is still no clear understanding of what determines the proximity length and what the underlying control mechanism is. Here, we achieved scalability of the OOT proximity effect in SrRuO3 (SRO) by epitaxial strain near the SRO/SrTiO3 heterointerface. We demonstrated that the OOT proximity length scale of SRO is extended from 4 unit cells to 14 unit cells by employing advanced scanning transmission electron microscopy. We also suggest that this variation may originate from changes in phonon dispersions due to electron–phonon coupling in SRO. This study will provide in-depth insights into the structural gradients of correlated systems and facilitate potential device applications.

Overcharging is expected to be one of the solutions to overcome the current energy density limitation of lithium‐ion battery cathodes, which will support the rapid growth of the battery market. However, high‐voltage charging often poses a major safety threat including fatal incendiary incidents, limiting further application. Numerous researches are dedicated to the disadvantages of the overcharging process; nonetheless, the urgent demand for addressing failure mechanisms is still unfulfilled. Herein, it is revealed that overcharging induces phase heterogeneity into layered and cobalt oxide phases, and consequent “twin‐like deformation” in lithium cobalt oxide. The interplay between the uncommon cobalt(III) oxide and the deformation is investigated by revealing the atomistic formation mechanism. Most importantly, abnormal cracking is discovered in the vicinity of the cobalt oxide where structural instability induces substantial contraction. In addition, surface degradation is widely observed in the crack boundary inside the particle. As unintentional overcharging can occur due to local imbalance in state‐of‐charge in severe operating conditions such as fast charging, the issues on overcharging should be emphasized to large extent and this study provides fundamental knowledge of overcharge by elucidating the crack development mechanism of layered cathodes, which is expected to broaden the horizon into high voltage operation.

Ruddlesden–Popper oxides (A2BO4) have attracted significant attention regarding their potential application in novel electronic and energy devices. However, practical uses of A2BO4 thin films have been limited by extended defects such as out‐of‐phase boundaries (OPBs). OPBs disrupt the layered structure of A2BO4, which restricts functionality. OPBs are ubiquitous in A2BO4 thin films but inhomogeneous interfaces make them difficult to suppress. Here, OPBs in A2BO4 thin films are suppressed using a novel method to control the substrate surface termination. To demonstrate the technique, epitaxial thin films of cuprate superconductor La2‐xSrxCuO4 (x = 0.15) are grown on surface‐reconstructed LaSrAlO4 substrates, which are terminated with self‐limited perovskite double layers. To date, La2‐xSrxCuO4 thin films are grown on LaSrAlO4 substrates with mixed‐termination and exhibit multiple interfacial structures resulting in many OPBs. In contrast, La2‐xSrxCuO4 thin films grown on surface‐reconstructed LaSrAlO4 substrates energetically favor only one interfacial structure, thus inhibiting OPB formation. OPB‐suppressed La2‐xSrxCuO4 thin films exhibit significantly enhanced superconducting properties compared with OPB‐containing La2‐xSrxCuO4 thin films. Defect engineering in A2BO4 thin films will allow for the elimination of various types of defects in other complex oxides and facilitate next‐generation quantum device applications.

This work has investigated the microstructure characteristics of high-quality alpha-Ga2O3 thin film grown on the Al2O3 single crystal substrate membrane. Hetero-epitaxial alpha Ga2O3 crystals reveal the formation of a three-fold symmetry at the initial stage of the growth by the oxygen template provided by the Al2O3. Inversion domains are found, and they have a 180° inverted configuration from the surroundings. These IDs lead to extra diffraction spots when observed along [110] and [010].

This work investigates the relationship between atomic arrangement and luminescence properties in a high-quality alpha-Ga2O3 thin film grown on an Al2O3 single-crystal membrane. The strain induced by merging domain boundaries shows more significant variability in annular darkfield images even though there is no additional gallium concentration confirmed. The bandgap energy of alpha-Ga2O3 is estimated to be 5.56 eV from the CL measurement in a transmission electron microscope. A peak at 320 nm was observed within the domain, while the domain boundary showed spectrum peaks with 380–480 nm. The anti-phase domain (APD) is formed by the instabilities of Al–O bonding templates provided by the Al2O3 substrate. The APD boundary gives a characteristic wavelength of 350 nm, which is the result of the merging boundary of in-phase and anti-phase domains.