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 PrNiO2 and SrCuO2 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 higher-order exchange interactions, we derive the correlation factor U/t for both compounds. A key finding is that despite a smaller Coulomb repulsion U, PrNiO2 exhibits a correlation strength that is 20% stronger than that of its isostructural cuprate counterpart SrCuO2. This indicates that a moderation of the correlation strength may further optimize superconductivity in nickelates.
@article{arxiv.2511.09460,
title = {Impact of Electron Correlations on Infinite-Layer Cuprates and Nickelates},
author = {Xunyang Hong and Yuetong Wu and Ying Chan and Sze Tung Li and I. Biało and L. Martinelli and A. Drewanowski and Qiang Gao and Xiaolin Ren and Xingjiang Zhou and Zhihai Zhu and A. Galdi and D. G. Schlom and K. M. Shen and J. Choi and M. Garcia Fernandez and Ke-Jin Zhou and N. B. Brookes and H. M. Rønnow and Qisi Wang and J. Chang},
journal= {arXiv preprint arXiv:2511.09460},
year = {2025}
}