Fig. 1: Simulated multislice ptychography reconstruction of infinite layer nickelates with residual oxygen.
a Schematic representation of the 4D-STEM experimental setup, illustrating the use of an over-focused convergent electron probe scanning the sample in real space, while a Merlin direct detector captures the convergent diffraction patterns in Fourier space. b Reconstructed three-dimensional phase-contrast images of the NdNiO2+x sample, highlighting fully occupied basal oxygen sites and partially occupied apical oxygen sites. c Supercell structural model of the NdNiO2+x sample, showcasing the spatial arrangement of apical and basal oxygen atoms, used for integrated center of mass (iCoM) and multi-slice ptychography simulations. The dashed circles indicate the partially occupied (35% occupancy in depth direction) apical oxygen. d Simulated iCoM image of the oxygen lattice. e Line profile of normalized oxygen signal intensity for basal and apical oxygen, extracted along the white dashed line e in d. f Phase-contrast image simulated using multi-slice ptychography (Mpty), capturing detailed depth information. The scale bars in image d and image f represent a length of 0.39 nm. g Basal oxygen depth profile along the white arrow g in f. h Apical oxygen depth profile along the white arrow h in f. i Line profile of normalized oxygen signal intensity for basal and apical oxygen, extracted along the white dashed line i in f. The scale bar in image d and image f represents a length of 0.39 nm.
