Daily Overview: Today’s highlight focuses on a deeper understanding of the electronic structure of hybrid Ruddlesden-Popper nickelates. A study combining symmetry-based phenomenological theory with DFT+DMFT calculations reveals the unconventional superconducting pairing mechanism of La₅Ni₃O₁₁: its monolayer subsystem resides in a Mott insulating state, and the low-energy physics is governed by e_g orbitals within the bilayer NiO₂ planes, exhibiting a two-gap feature. The dominant interlayer pairing stems from the d_z² orbital, while the subdominant intralayer pairing arises from the d_{x²−y²} orbital. Compared with the bilayer La₃Ni₂O₇, the superconducting transition temperature of this material decreases to approximately 64 K (relative to 80 K), which is quantitatively attributed to a reduction in the interlayer pairing contribution caused by the decrease in the hopping parameter ratio |t_⊥^z/t_∥^x|. This finding highlights the critical role of the γ hole pockets within the bilayer NiO₂ planes for superconductivity, providing a microscopic picture for a unified understanding of the pairing differences in analogous nickelate superconductors. arXiv submission processing window: 2026-07-22 00:00 to 2026-07-22 00:00 UTC.

1. Symmetry-Based Microscopic Theory of the Unconventional Pairing Mechanism in La$_5$Ni$_3$O$_{11}$

Summary: This study develops a symmetry-based phenomenological theoretical framework for the unconventional superconducting pairing mechanism in the mixed nickelate La(5)Ni(3)O({11}). Using charge self-consistent density functional theory combined with dynamical mean-field theory (DFT+DMFT), the authors find that the monolayer subsystem resides in a Mott insulating state and the low-energy physics is governed by the Ni-(e_g) orbitals of the bilayer subsystem. Analysis reveals that superconductivity in La(5)Ni(3)O({11}) exhibits a two-gap character: the dominant interlayer pairing stems from the (d{z^2}) orbital, while the subdominant intralayer pairing originates from the (d{x^2-y^2}) orbital. Compared with bilayer La(_3)Ni(2)O(7), its lower superconducting transition temperature (about 64 K versus 80 K) is attributed to a weakened interlayer pairing contribution, quantitatively reflected by a decrease in the hopping parameter ratio (|t\perp^z / t\parallel^x|). This unified picture highlights the crucial role of the (\gamma) hole pocket in the bilayer NiO(_2) planes for superconductivity, providing a microscopic basis for understanding the differences in pairing mechanisms among analogous nickelate superconductors.