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This study points out that Zhu et al., when measuring the superconducting volume fraction of pressurized Ruddlesden-Popper nickelate La₄Ni₃O₁₀, employed a previously unreported calculation equation, leading to a significant overestimation of the results. By reanalyzing the original data published by Zhu et al. using standard methods for calculating superconducting magnetic moments, the authors found that the superconducting volume fraction is only 51% to 59%, rather than the 81% to 86% reported by Zhu et al. Upon examining the equation and its derivation provided by Zhu et al., the authors discovered that the equation mistakenly used sample geometry parameters in its calculation, resulting in an approximately two-fold overestimate of the volume proportion occupied by the superconducting phase. Using a hypothetical sample as an example, the authors demonstrate that even if the superconducting phase actually accounts for only 50%, this equation would still yield a result close to 100%. Consequently, this error affects all previously reported superconducting volume fraction data for Ruddlesden-Popper nickelates, necessitating a re-evaluation of these conclusions.

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This paper employs neural quantum states, in particular hidden fermion determinant states (HFDS), to perform a scalable variational study of the three-band Emery model for CuO2/NiO2 planes in cuprates and nickelates. The authors first benchmark against matrix product states on width-two geometries and then simulate fully two-dimensional systems up to 10×10 unit cells (300 sites), characterizing the momentum-space distribution of dopants and finding an electron-hole dichotomy similar to that observed in cuprate experiments. The study further downfolds the three-band model to an effective single-band description by constructing interacting Wannier functions, with parameters covering the cuprate charge-transfer regime, the nickelate Hubbard-Mott regime, and scans of the charge-transfer gap. The results show that the effective model deviates significantly from the usual Fermi-Hubbard model: U/t is enhanced, some parameters exhibit pronounced doping dependence, and important terms beyond the conventional Hubbard model emerge, most notably the density-assisted hopping t_n; moreover, t_n makes the largest contribution to particle-hole asymmetry, rather than next-nearest-neighbor hopping. The effective parameters depend sensitively on the charge-transfer energy, doping, and interaction ratio. The conclusion is that HFDS is an efficient tool for studying the two-dimensional Emery model, and that a single-band description may need to include new interaction terms generated by the underlying multiband model.

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This study addresses the controversy over the superconducting pairing symmetry of the high-pressure bilayer nickelate La₃Ni₂O₇ by employing a full-spectrum model based on orthogonalized projection (the Oroj method), which projects Kohn–Sham states onto local Ni-e_g orbitals and, while preserving the density functional theory band structure, redistributes spectral weight over a wider energy range, thereby incorporating Ni–O hybridization and contributions from electronic states away from the Fermi surface. Compared with a Wannier model that describes only the low-energy bands near the Fermi surface, this full-spectrum model significantly enhances interlayer spin fluctuations and yields a commensurate magnetic instability; within the spin-fluctuation framework, such features favor the formation of a sign-changing s±-wave superconducting state, whereas the low-energy model tends toward d-wave pairing. The results indicate that interlayer coupling and Ni–O hybridization in the full-energy description play an important stabilizing role in theoretical predictions of the superconducting pairing symmetry of bilayer nickelates.

This study systematically characterizes the evolution of unoccupied states in the infinite-layer nickel oxide La₁₋ₓCaₓNiO₂ as a function of doping and temperature using O K-edge and Ni L-edge X-ray absorption spectroscopy. Superconductivity emerges in the doping range of x = 0.18 to 0.27. Near x ≈ 0.20–0.23, a redistribution of low-energy spectral weight occurs: Ni 3d-dominated states decrease while O 2p hybridized states increase, indicating an orbital-selective crossover in Ni–O covalency. This crossover coincides precisely with the sign reversal of the Hall coefficient and precedes the suppression of the superconducting critical temperature at higher doping levels. By directly linking transport anomalies and the superconducting dome to measurable Ni–O orbital reorganization, these results represent a critical step toward establishing a unified orbital-resolved phase diagram for infinite-layer nickelates and offer a practical route for designing superconductivity through hybridization engineering.

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This paper investigates the orbital-antiphase structure of the superconducting gap in high-temperature superconductivity in the bilayer nickelate La3Ni2O7 induced by pressure or compressive strain, building on the notion that the normal-state electronic structure can give rise to bonding–antibonding s±-wave or d-wave pairing. Using an effective four-orbital model, the authors first analyze the gap-node conditions in a single-layer two-orbital model, then extend the analysis to the bilayer system, and employ the bonding/antibonding basis to relate the nodal characteristics to the signs and relative magnitudes of the intralayer and interlayer pairing components. The results show that when the gap changes sign between the orbitals involved in pairing, additional node pairs appear on the α and/or β Fermi surface sheets in addition to symmetry-enforced nodes; these nodes are not required by the symmetry of the gap function and can be detected by ARPES. Moreover, the orbital-antiphase gap modifies the temperature dependence of the low-temperature superfluid stiffness, providing concrete experimental criteria for testing this superconducting state in bilayer nickelates and related multiorbital systems.