Interface of the CTO film and the LSAT substrate with a transition layer of a different BO₆ rotation pattern. Panel (a) shows the STEM HAADF and ABF images of the CTO/LSAT interface along [110]_pc axis, with overlapped polyhedral model and one simulated ABF image (inset). The [001]_pc direction for both oxides is the out-of-plane direction, which is the film growth direction. Panel (b) displays the averaged profile of θ. θ is an inclination angle between the major axis of the contrast ellipse of oxygen and horizontal La–La direction. The solid squares refer to measured values, and the empty squares represent the speculated values for the LSAT substrate, where there is no well-defined deviation from roundness to detect. Symmetries of BO6 rotation across the interfaces are displayed in overlaid colors (green, a⁰a⁰a⁰; white, a⁻b⁺?; purple, a⁻ b⁺c⁰; blue −a⁻ b⁺c⁻), which are determined from θ angle measurement as well as other analysis, such as PCA (see text and Supporting Information). In contrast to the case of the LSMO/ESMO interface, a different BO₆ rotation pattern (purple, a⁻b⁺c⁰) is found in the transitional layer at the interface. Reproduced from Ref. [26].