Role of interstitial s orbital in a model of infinite-layer nickelates

This is the authors' abstract. We don't add key points for this paper.

Motivated by recent angle-resolved photoemission spectroscopy (ARPES) experiments on infinite-layer (IL) nickelates, we employ determinant quantum Monte Carlo (DQMC) to study the three-orbital Emery model (d-p model) coupled to an additional interstitial s orbital retaining the three-dimensional dispersion. Our large-scale simulations reveal that: (1) the interstitial s-orbital-derived electron pocket is significantly reduced by the strong interaction but persists upon 20% hole doping, reaching a size comparable to experimental observations; (2) the dx²-y²-orbital dispersion is strongly renormalized by interactions, leading to a weak kz dependence consistent with ARPES measurements. Furthermore, compared with the conventional three-orbital d-p model, the d-p-s model exhibits enhanced short-range antiferromagnetic correlations. These results highlight the crucial role of strong correlations and multi-orbital effects in shaping the low-energy electronic structure and many-body correlations in IL nickelates, and demonstrate the necessity of treating interaction-driven many-body physics within a realistic multi-orbital framework.