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By combining density functional theory, dynamical mean-field theory, and the random phase approximation to solve the superconducting gap equation, researchers have discovered that hole-doped layered nickel oxide La₃₋ₓSrₓNi₂O₇ can achieve bulk superconductivity under ambient pressure. When the doping concentration x approaches 0.4, the γ Fermi pocket derived from the Ni-d₃z²₋r² orbital evolves from a circular to a diamond shape and expands to half the Brillouin zone, forming a nearly perfect Fermi surface nesting with an optimal nesting vector Q=(π, π). This structure significantly enhances antiferromagnetic spin fluctuations, elevating the superconducting eigenvalue to experimentally observable levels without the need for high pressure or strain. This work elucidates the mechanism by which hole doping modulates the shape and size of the Fermi pocket, providing a theoretical foundation and an experimentally feasible pathway for realizing the long-sought bulk superconductivity in such materials under ambient conditions.

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.