Paper

Daily Overview: Today’s highlight work focuses on an in-depth understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. [1] By employing Ni L₃-edge resonant inelastic X-ray scattering, a systematic comparison was made of the spin excitations in the octahedral-phase Nd₉Ni₈O₂₅ (non-superconducting) and its reduced planar-phase counterpart Nd₉Ni₈O₁₈ (with approximately 5 K superconducting correlations). This comparison reveals fundamental differences in the ground state and magnetic excitations between the two structural families: the octahedral phase exhibits a spin-density-wave ground state, whereas the planar phase displays an elastic peak at (1/3,0) with dispersiveless magnetic excitations. These findings provide key experimental evidence for understanding the microscopic mechanism of nickelate superconductivity, highlighting the decisive role of the coordination environment in shaping the electronic structure and superconducting correlations. arXiv submission processing window: 2026-03-30 00:00 to 2026-03-30 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-03-30

Daily Overview: Today’s highlights focus on deepening the understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. In [1], a study based on high-brightness synchrotron radiation X-ray diffraction precisely determined the polar structure (space group Ima2) of La₃Ni₂O₇, revealing a previously overlooked glide mirror symmetry breaking. By analyzing bond length differences, it confirmed a checkerboard charge order state at nickel sites, which competes with pressure-induced superconductivity. This finding provides a critical structural basis for understanding the phase competition mechanism in bilayer nickelates. In [2], from a theoretical perspective, a systematic study of the bilayer Kondo lattice model was conducted using single-site dynamical mean-field theory. It was found that interlayer spin coupling or hole doping can drive a non-Fermi liquid critical point, separating the overdoped Fermi liquid from the underdoped pseudogap metal (i.e., the “second Fermi liquid”). Mapping this model to La₃Ni₂O₇, it predicts that current experimental samples lie in the overdoped Fermi liquid region, while electron doping is expected to access the pseudogap phase and the non-Fermi liquid critical regime, offering theoretical guidance for exploring anomalous metallic behavior in such materials. These two works deepen the understanding of charge order, pseudogap, and non-Fermi liquid behavior in nickel-based superconductors from experimental and theoretical perspectives, respectively. arXiv submission processing window: 2026-03-27 00:00 to 2026-03-27 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-03-27

Daily Overview: Today’s highlights focus on deepening the understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. In [1], the superfluid density of infinite-layer Nd1-xSrxNiO2 was systematically measured using the mutual inductance method, revealing a weak superfluid stiffness with a square-root dependence on Tc. Unexpectedly, a strong coupling between Nd 4f magnetic moments and the superfluid was found to significantly suppress the superfluid density, suggesting that the interplay between magnetic order and the superconducting phase limits Tc. [2] constructed a microscopic theory of triplon-mediated superconducting pairing in bilayer nickel oxides, explaining the experimentally observed features of the α-band—namely, its small density of states but larger energy gap—as well as the momentum-space anisotropy of the gap. This provides strong support for triplon mediation as the pairing mechanism in this system. [3] investigated the spin-density wave (SDW) transition in trilayer Pr4Ni3O10 through oxygen isotope substitution and pressure experiments, finding that the isotope shift does not vary with pressure. This indicates that the SDW transition is primarily driven by electronic correlations rather than lattice dynamics, in contrast to the doping-enhanced isotope effect in cuprates, providing key constraints for understanding the electronic origin of density-wave order in nickelates and its relationship with superconductivity. [4] employed quantum Monte Carlo simulations with a multi-orbital model incorporating interstitial s orbitals to reproduce experimental features of infinite-layer nickelates, such as the persistence of an electron pocket at 20% doping and strong renormalization of d-orbital dispersion. The study also found that s orbitals significantly enhance short-range antiferromagnetic correlations, revealing the decisive role of multi-orbital strong correlation effects on low-energy electronic states and spin correlations. These studies deepen the understanding of nickel-based superconducting systems from multiple dimensions, including superfluid response, pairing mechanisms, the origin of density waves, and multi-orbital electronic structure. arXiv submission processing window: 2026-03-24 00:00 to 2026-03-24 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-03-24

Daily Overview: The highlights of today’s work focus on the in-depth understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. A review systematically summarizes the discovery, synthesis methods, and electronic properties of superconductivity in bilayer La₃Ni₂O₇ and trilayer La₄Ni₃O₁₀, emphasizing the importance of developing ambient-pressure superconducting phases. Another magnetotransport study observes the coexistence of linear-in-H magnetoresistance and T² resistivity in the normal state of overdoped infinite-layer La₁₋ₓSrₓNiO₂, providing key constraints for understanding the normal-state transport properties of this system. Meanwhile, theoretical work reveals, through multi-orbital cluster calculations, the redistribution of oxygen hole states in La₄Ni₃O₁₀ under pressure, identifying a transition in the hole localization mode between the central and outer layers, and elucidating similarities with the bilayer system in terms of spin-ordered states. These results collectively advance the understanding of the electronic structure, pairing mechanisms, and pressure effects in nickel-based superconductors. arXiv submission processing window: 2026-03-19 00:00 to 2026-03-19 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-03-19

Daily Overview: Today’s highlights focus on the in-depth understanding of the electronic structure of hybrid Ruddlesden-Popper nickelates. Using first-principles calculations, the researchers systematically revealed the crystal and electronic structural responses of La₇Ni₅O₁₇ under hydrostatic pressure and biaxial compressive strain, identifying a dynamically stable low-symmetry C2/c structure. It was found that both pressure and strain suppress octahedral tilting, leading to tetragonalization of the structure. The key difference lies in the Fermi level position of the d_z² bonding band in the trilayer block: under hydrostatic pressure, this band crosses the Fermi level at 30 GPa, whereas compressive strain consistently keeps it below the Fermi level. This strain-induced change in electronic structure is highly consistent with the behavior observed in conventional bilayer nickelates, providing crucial insights into the differentiated regulation of superconductivity by pressure and strain in this material system. arXiv submission processing window: 2026-03-18 00:00 to 2026-03-18 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-03-18