Fig. 1: Atomic displacement and oxygen vacancies at the LAO/KTO interface.

a A schematic drawing of the KTO crystalline structure. b The iDPC-STEM image with atomic resolution. The dashed line denotes the boundary between LAO and KTO. c The amplified view of atoms in the yellow box of panel (b). The relative displacement between K and Ta atoms is denoted by δ. δ is substantial (~0.54 Å) right at the LAO/KTO interface and quickly approaches zero for atoms distant from the interface. Concomitantly, some oxygen atoms are clearly missing at the interface (open circles). d, e The amplified view of atoms in boxes 1 and 2 of panel (c), respectively. The atomic structures close to and far away from the interface show remarkable differences. f The measured δ as a function of N, where N is the number of Ta–O plane counting from the interface. g The line profile (corresponding to the purple dashed line in panel (c)) shows the locations of oxygen atoms, which are missing in the vicinity of the interface.