Fig. 1. Characterization of perovskite NdNiO3, oxygen-deficient NdNiO2+x and infinite-layer NdNiO2.
a, Cu Kα θ–2θ XRD measurements of a sequence of thin films ranging from NdNiO3 (sample A) to partially reduced NdNiO2+x (samples B and C) and NdNiO2 (samples D–F). b, Electrical transport measurements of the same series of samples. c, Total-electron-yield (TEY) XAS measurements of this sample series taken at the Ni L3 edge with the electric field ε parallel to the sample a axis. d,e, RSXS measurements of NdNiO2 samples D–F; rocking curves through the nominal charge order position of q = (–1/3, 0) at the Ni L3 (d) and Nd M5 (e) edges at σ and π polarizations, respectively. The plotted intensity is the measured scattered intensity I divided by the incident-beam intensity I0, without any background subtraction. Traces in a and c–e have been vertically offset for clarity.