Ruddlesden-Popper nickelates offer a new route to high-temperature superconductivity beyond the cuprates and iron-pnictides. However, the electronic reorganization that enables superconductivity in bilayer nickelates remain unresolved, largely due to the difficulty of directly probing the superconducting phase. Here, we overcome this limitation by stabilizing superconducting (La,Pr)3Ni2O7 thin films with a protective capping layer, thereby enabling direct spectroscopic access via X-ray absorption and resonant inelastic X-ray scattering. We resolve the evolution of in-plane and out-of-plane electronic states, spin and orbital excitations, and spin-density-waves across insulating, superconducting, and metallic regimes. Combining experimental results with theoretical analysis, we show that the in-plane dx2−y2 states form an itinerant backbone, while superconductivity emerges only when coherent dz2-pz-dz2 interlayer hybridization develops, accompanied by suppressed static spin order and strongly damped spin excitations. Oxygen stoichiometry and epitaxial strain both act on this interlayer channel, placing superconductivity within a narrow window of interlayer coherence and correlation strength. These findings identify the microscopic ingredients required for superconductivity in bilayer nickelates and provide a multiorbital picture of its emergence.
@article{arxiv.2604.14701,
title = {Interlayer hybridization enables superconductivity in bilayer nickelates},
author = {Shilong Zhang and Meng Zhang and Qilin Luo and Zihao Tao and Hsiao-Yu Huang and Kunhao Li and Ganesha Channagowdra and Jie Li and Junchi Fu and Di-Jing Huang and Yanwu Xie and Yi Lu and Yingying Peng},
journal= {arXiv preprint arXiv:2604.14701},
year = {2026}
}