Extended Data Fig. 2: High-resolution HAADF- and ABF-STEM imaging of Nd_0.85Sr_0.15NiO₂ film on LSAT.

a, High-resolution HAADF- (left) and annular bright-field (ABF)- (right) STEM images of the Nd_0.85Sr_0.15NiO₂ film on LSAT shown in Fig. 1b. Both the lattice size and oxygen column structure visible in the ABF image are consistent with the infinite-layer structure. Atomic model overlays show columns of Nd/Sr (orange), Ni (purple), La/Sr (green), Al/Ta (blue), and O (red). b, HAADF-STEM image of the same Nd_0.85Sr_0.15NiO₂ film on LSAT. c. Quantitative tracking of the local c-axis lattice constant measured between consecutive A-site planes (e.g., Nd to Nd). The lattice constant within the film shows good agreement with the expected value for the infinite-layer structure and the measurements of a fully reduced film by XRD. Scale bars, 5 Å.