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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. ...

arXiv Daily: nickelate superconductors 2026-07-22

Daily Overview: Today’s highlights focus on the microscopic pairing theory of the hybrid Ruddlesden–Popper nickelate La₅Ni₃O₁₁, while multifaceted studies of infinite-layer nickelate superconductors also reveal a series of key advances ranging from orbital-selective electron correlations to strange-metal critical behavior. Theoretically, a symmetry-based study combining DFT+DMFT indicates that superconductivity in La₅Ni₃O₁₁ arises from two-gap pairing of the Ni-e_g orbitals within the bilayer subsystem, where coupling of the interlayer d_{z²} orbital dominates the pairing, and the variation in transition temperature can be attributed to the decreasing ratio of interlayer to intralayer hopping parameters. Meanwhile, the global phase diagram of the bilayer two-orbital Hubbard model unifies seemingly contradictory phenomena in La₃Ni₂O₇—including orbital-dependent effective mass enhancement, downward shift of the bonding band, and a sharp drop in Drude weight—highlighting the critical role of interlayer antiferromagnetic superexchange in sustaining band splitting. In infinite-layer systems, high-quality ARPES measurements resolve well-defined quasiparticle peaks in La₀.₈Ca₀.₂NiO₂ for the first time, revealing momentum-dependent linear scattering in the imaginary part of the self-energy and marginal Fermi liquid behavior without any detectable pseudogap, suggesting that a pseudogap is not a prerequisite for high-temperature superconductivity. Another experiment directly observes zero resistance and a diamagnetic response in stoichiometric PrNiO₂ thin films, confirming intrinsic superconductivity of the parent compound; this superconducting phase is confined to an extremely narrow window of less than about 3% extra hole doping, well separated from the known ~20% doping superconducting dome, thereby forming a unique double-superconducting-region structure and exhibiting stronger upper critical field anisotropy. Furthermore, employing the Seebeck coefficient as a probe of heat capacity, a low-temperature logarithmic divergence is discovered at the critical doping point x* in infinite-layer nickelates, indicating that x* is a quantum critical point where the pseudogap phase terminates; the abrupt change in doped carrier density recapitulates the hallmark of the cuprate pseudogap, while the emergent T-linear resistivity around x* provides compelling evidence for the quantum critical origin of strange-metal behavior. arXiv submission processing window: 2026-07-21 00:00 to 2026-07-21 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-07-21

Daily Overview: Today’s highlighted work focuses on the microscopic theoretical elucidation of the magnetic ground state of the bilayer Ruddlesden–Popper nickelate La₃Ni₂O₇. Based on an orbital-selective Mott physics picture, the study describes the system as consisting of itinerant d_{x²−y²} quasiparticles coexisting with localized d_{z²} magnetic moments, and by integrating superexchange and RKKY interactions, reveals a magnetic frustration mechanism dominated by long-range coupling mediated by itinerant electrons. Theoretical calculations naturally yield a non-coplanar antiferromagnetic ground state consistent with neutron scattering experiments; the softening of the spin-wave spectrum at the ordering wave vector and the total bandwidth of about 80 meV are also consistent with resonant inelastic X-ray scattering data, indicating that orbital-selective correlations are the core factor determining the magnetism of bilayer nickelates and suggesting that low-energy magnetic fluctuations may provide the driving force for unconventional superconducting pairing. arXiv submission processing window: 2026-07-17 00:00 to 2026-07-17 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-07-17

Daily Overview: Today’s highlighted work centers on an in-depth understanding of the electronic structure of hybrid Ruddlesden–Popper nickelates. On the one hand, a theoretical study proposes a dual‑parameter control framework based on in‑plane d_(x²–y²) orbital filling and effective interlayer antiferromagnetic superexchange, providing a unified explanation for the systematic variation of the superconducting transition temperature in the bilayer nickelate La₃Ni₂O₇ under pressure, composition, and strain. It explicitly indicates that clean electron doping can enhance pairing strength, whereas oxygen vacancies suppress superconductivity by disrupting exchange pathways and inducing disorder effects. On the other hand, a high‑pressure single‑crystal structural investigation of the trilayer nickelate La₄Ni₃O₁₀ clarifies its direct transition path from the tetragonal to the monoclinic phase, reveals that pressure effectively stabilizes tetragonal symmetry, and detects faint structural distortions associated with density‑wave order. These findings provide key crystallographic evidence for the consensus that superconductivity emerges upon restoring the tetragonal phase under high pressure. Together, these two studies—from theory and experiment—deepen our understanding of the cooperative interplay among charge, spin, and lattice degrees of freedom in nickelates, and jointly point to a viable strategy for optimizing superconducting properties by controlling interlayer coupling and structural symmetry. arXiv submission processing window: 2026-07-16 00:00 to 2026-07-16 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-07-16

Daily Overview: Today’s highlight work focuses on the s+id mixed superconducting state induced by the synergistic effect of electronic correlations and electron-phonon coupling in infinite-layer nickelate superconductors. Investigations based on a combination of first-principles calculations and the fluctuation-exchange Migdal-Eliashberg theory reveal that spin fluctuations drive robust d-wave pairing in the Ni d_{x^2-y^2} orbital, while electron-phonon coupling induces an s-wave component in the interstitial orbitals. These two mechanisms synergistically form an s+id mixed superconducting state at a specific carrier density (e.g., n=0.9). The stability of this mixed state is highly sensitive to the local electron density. Local oxygen defects, by modulating the electron density, can create finite-sized domains with different pairing symmetries, thereby providing a microscopic explanation for the spatially inhomogeneous superconducting gap observed experimentally. These results profoundly underscore the crucial role of the synergy between correlation effects and electron-phonon coupling in determining the pairing symmetry of nickelate superconductors. arXiv submission processing window: 2026-07-15 00:00 to 2026-07-15 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-07-15