Impact of electron correlations on infinite-layer cuprates and nickelates

Abstract Optimization of unconventional superconductivity involves a balance of interaction strengths. Precise determination of correlation strength across different material families is therefore important. Here, we present a combined X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) study of infinite-layer PrNiO 2 and SrCuO 2 that enables fair comparison of their interaction strengths. For both compounds, we study the orbital and magnetic excitations and extract their dispersions along high-symmetry directions. Using a single-band Hubbard model and including physically plausible assumptions about higher-order exchange interactions, we estimate the correlation factor U / t for both compounds. A key finding is that despite the prediction of a smaller Coulomb repulsion U , PrNiO 2 exhibits a correlation strength U / t that is 20% stronger than that of its isostructural cuprate counterpart SrCuO 2 . This indicates that moderation of the correlation strength may further optimize superconductivity in nickelates.