Oxygen Hole Character and Lateral Homogeneity in PrNiO2+δ Thin Films

Using x-ray absorption spectroscopy with lateral resolution from the submillimeter to submicrometer range, we investigate the homogeneity, the chemical composition, and the nickel 3 d - oxygen 2 p charge transfer in topotactically reduced epitaxial PrNiO 2+ δ thin films. To this end, we use x-ray absorption spectroscopy in a standard experimental setup and in a soft x-ray microscope to probe the element and spatially resolved electronic structure modifications through changes of the nickel-2 p and oxygen-1 s absorption spectrum upon soft-chemistry reduction. We find that the reduction process is laterally homogeneous across a partially reduced PrNiO 2+ δ thin film sample for length scales down to 50 nm.