Direct observation of charge order in an epitaxial NdNiO₃ film

The first direct observation of charge order of Ni3+δ′ and Ni3-δ by resonant x-ray scattering experiments in an epitaxial film of NdNiO3 was presented. A quantitative value of δ+δ′ = (0.45± 0.04)e was obtained. Results showed that temperature dependence of the charge order deviated significantly from those of the crystallographic structure and magnetic moment.