Paper

Daily Overview: Today’s highlight focuses on advancing the understanding of the electronic structure of hybrid Ruddlesden-Popper nickelates. Using Raman scattering spectroscopy, the research team comprehensively characterized the electronic, magnetic, and lattice excitations of the bilayer nickelate La₃Ni₂O₇ under ambient pressure. For the first time, they simultaneously observed two types of in-plane spin exchange interactions along the Ni-O bond direction and the diagonal direction in the spin-density-wave state, revealing the bond-diagonal antiferromagnetic competition mediated by the nickel d_{x²-y²} orbitals. Moreover, the discovery of low-energy two-magnon excitations provides direct spectroscopic evidence for spin disproportionation, while anomalous phonon softening hints at an incipient lattice instability. These results collectively establish the correlation among competitive spin interactions, spin disproportionation, and lattice response in this system, providing key experimental foundations for understanding the microscopic mechanism of nickelate superconductivity. arXiv submission processing window: 2026-02-05 06:39 to 2026-02-05 06:39 UTC. ...

arXiv Daily: nickelate superconductors 2026-02-05

Daily Overview: Today’s highlight focuses on advancing the understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. In [1], a theoretical study based on a two-leg t-J-J⊥ ladder model reveals the existence of a generalized Luther-Emery liquid phase under finite layer polarization, which exhibits incommensurate pairing density wave correlations. This phase features a finite spin gap, with interlayer pairing correlations displaying FFLO-like oscillations, and the iC-PDW state remains robust across a wide range of doping and polarization. The authors specifically note that this model is highly relevant to the physical picture of the bilayer nickelate La₃Ni₂O₇, offering a new theoretical perspective for understanding the pairing mechanism in such nickel-based superconducting systems. arXiv submission processing window: 2026-02-04 19:00 to 2026-02-04 19:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-02-04

Daily Overview: Today’s highlighted work focuses on deepening the understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. In [1], using high-resolution ARPES combined with dynamic mean-field theory calculations, the research team discovered an orbital-selective Mott phase in Pr₄Ni₃O₁₀ driven by the reduction of interlayer Ni-O-Ni bond angles (from 165° to 158°). In this phase, the d_z² orbital becomes highly incoherent due to geometric frustration, while the d_{x²-y²} band remains coherent, providing a specific framework of lattice-orbital-spin coupling for understanding the emergence of nickel-based superconductivity under high pressure. Furthermore, in [2], based on first-principles path integral molecular dynamics, a novel lattice quantum disorder (LQD) phase was revealed in the bilayer nickelate La₃Ni₂O₇. This phase precisely aligns with the left boundary of the superconducting dome in the pressure-temperature phase diagram, and its maximum superconducting transition temperature is consistent with experimental observations. This indicates that nuclear quantum fluctuations may provide a pairing mechanism for high-temperature superconductivity beyond the conventional phonon picture, a finding directly relevant to the core issue of lattice degrees of freedom and electronic pairing in nickel-based superconductors. arXiv submission processing window: 2026-02-03 14:25 to 2026-02-03 15:39 UTC. ...

arXiv Daily: nickelate superconductors 2026-02-03

Daily Overview: Today’s highlights focus on an in-depth understanding of the electronic structure of triple-layer Ruddlesden-Popper nickelates. Two independent studies, employing polarization-resolved Raman scattering and micro-focused angle-resolved photoemission spectroscopy, respectively, systematically revealed the momentum selectivity and orbital dependence of the density-wave gap in Pr₄Ni₃O₁₀ and La₄Ni₃O₁₀. One work discovered that the spin density wave gap appears only on a subset of Fermi pockets, in stark contrast to the feature in the bilayer nickelate La₃Ni₂O₇, where only the β pocket exhibits an anisotropic gap, establishing distinct gap topologies across systems with different numbers of layers. The other study, by circumventing multidomain effects, for the first time clearly distinguished intrinsic and folded bands, confirming that the density wave is driven by inter-orbital Fermi surface nesting between the α and β bands, and observed extremely strong mass renormalization of the d_z² orbital (enhancement factor up to 16.7), successfully resolving the long-controversial splitting of the triple-layer β band. These results provide key microscopic constraints for understanding the relationship between density wave instabilities and superconductivity in nickelate superconductors. arXiv submission processing window: 2026-02-02 14:13 to 2026-02-02 14:46 UTC. ...

arXiv Daily: nickelate superconductors 2026-02-02

Daily Overview: Today’s highlight focuses on deepening the understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. In [1], the researchers combined high-resolution angle-resolved photoemission spectroscopy with a tight-binding model to systematically reveal the electronic structure of the trilayer nickel oxide La₄Ni₃O₁₀. For the first time, band splitting induced by interlayer coupling was experimentally observed, and a momentum-dependent density wave gap structure on the Fermi surface was resolved. Its origin can be attributed to interlayer antiferromagnetic spin density waves resulting from mirror-symmetry-selective Fermi surface nesting. This work also confirms the dominant role of the Ni-3d_z² orbital in low-energy physics, providing a key framework for understanding the formation mechanism of density wave order under ambient pressure and the correlation between pressure-induced superconductivity and interlayer spin fluctuations. arXiv submission processing window: 2026-01-30 06:01 to 2026-01-30 06:01 UTC. ...

arXiv Daily: nickelate superconductors 2026-01-30