Paper

Daily Overview: Today’s highlights focus on a multi-angle analysis of density waves, electronic structure characterization, and the superconducting pairing mechanism in hybrid Ruddlesden–Popper nickelates. In [1], ultrafast optical experiments reveal strong coupling between the density wave and the lattice in La₄Ni₃O₁₀ single crystals and demonstrate that ultrafast photoexcitation can non‑thermally suppress this order parameter, offering a new approach for the non‑equilibrium control of quantum states in nickelates. [2] develops a scanning tunneling microscopy/spectroscopy electronic theory for superconducting bilayer nickelate thin films, pointing out that the multi‑orbital character and the tip‑height‑dependent changes in spectral weight can distinguish the controversial γ‑band and β‑band coherence peaks, and that quasiparticle interference patterns can identify s‑wave or d‑wave pairing symmetry. [3] constructs a pairing model mediated by local d₃z²−r² spin‑triplet excitations (triplons), predicts an interband s±‑wave superconducting gap, and successfully explains the experimentally observed anomalous gap magnitude and the double‑peak structure in tunneling spectra, strongly supporting the triplon mechanism as the microscopic origin of unconventional superconductivity in nickelates. arXiv submission processing window: 2026-07-01 00:00 to 2026-07-01 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-07-01

Daily Overview: Today’s highlight work focuses on the in-depth understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. Based on unrestricted Hartree-Fock calculations, researchers have established a hierarchical order of spin density waves and charge density waves in La₃Ni₂O₇, providing key clues linking the ambient-pressure ordered phase to the high-pressure superconducting phase. Meanwhile, a first-principles study of the La₃Ni₂O₅F bilayer infinite-layer system reveals an E* band composed of interstitial-region electrons and the induced self-doping effect, leading to anomalous two-dimensional fluctuation behavior of the Ni¹⁺ magnetic moment. Regarding the pairing mechanism, by combining full-gap constraints from ARPES and STM with gap features along the Brillouin zone diagonal, a Hund’s rule-driven pairing picture dominated by the d_{x²-y²} orbital in La₃Ni₂O₇ is clarified, ruling out hybridization-driven and weak-coupling random phase approximation schemes. Furthermore, by extending infinite-layer nickelates to heavy rare-earth systems via high-pressure oxygen-assisted chemical synthesis and achieving hole doping through Eu valence changes, robust magnetic-field-reentrant superconductivity arising from the competition of 4f magnetic moments is observed at the phase diagram boundary, and Tc is elevated to 40.1 K through rare-earth ion exchange. These findings reveal the key role of 4f magnetic moments in modulating pairing strength and quantum criticality, providing a synthetic platform for exploring unconventional superconductivity and quantum phase transitions. arXiv submission processing window: 2026-06-30 00:00 to 2026-06-30 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-06-30

Daily Overview: Today’s highlight focuses on revealing a ubiquitous high-temperature structural phase transition in the Ruddlesden-Popper nickelate La$_{n+1}$Ni$_n$O$_{3n+1}$ series. Through multi-technique characterization across a broad temperature range, previously overlooked lattice-parameter anomalies were discovered in the n=2 and n=3 compounds at around 560 K: the bilayer phase exhibits a sudden increase in the out-of-plane lattice constant coupled with an in-plane contraction, indicating an abrupt release of octahedral tilting; in contrast, the monolayer–trilayer polymorphs display isotropic volume shrinkage, and the monoclinic angle β of the trilayer phase shows a clear kink. Heat capacity and DSC measurements confirm the thermodynamic nature of this transition. This high-temperature transformation is distinct from the known tetragonal transition and the low-temperature density-wave transitions, and it is absent in the n=∞ perovskite LaNiO₃. The study emphasizes that such high-temperature structural instability must be seriously considered for its potential impact on the low-temperature physical properties when exploring superconductivity in nickelates. arXiv submission processing window: 2026-06-26 00:00 to 2026-06-26 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-06-26

Daily Overview: Today’s highlighted work focuses on the significant enhancement of the phonon thermal Hall effect by density-wave order in the trilayer Ruddlesden–Popper nickelate La₄Ni₃O₁₀. The study reveals that upon the density-wave phase transition at around 140 K, the phonon thermal Hall response increases sharply: the thermal Hall angle rises from 1.5‰ at 160 K to over 6‰, and the thermal Hall resistivity exhibits a double-plateau feature. By comparing with the magnon–phonon dispersion crossing energy, it is confirmed that magnon–phonon hybridization induced by spin-density-wave order is the central mechanism behind this effect. This discovery uncovers strong spin–lattice coupling that governs phonon transport in nickelates, and suggests that such dynamic coupling may participate in suppressing antiferromagnetic order and promoting the emergence of superconductivity under high pressure through the softening of optical phonons, thereby offering a new perspective for understanding the cooperative evolution of charge, spin, and lattice degrees of freedom in unconventional superconductors. arXiv submission processing window: 2026-06-24 00:00 to 2026-06-24 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-06-24

Daily Overview: Today’s highlights focus on an in-depth understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. In [1], functional renormalization group studies reveal that lattice symmetry is a core factor in regulating the competition between spin density wave and superconductivity in bilayer nickelate La₃Ni₂O₇, suggesting that suppressing orthorhombic distortion via uniaxial strain may achieve bulk superconductivity at ambient pressure. [2] systematically compares the strain effects in trilayer La₄Ni₃O₁₀ thin films, finding that while compressive strain can suppress density wave order, it cannot completely eliminate in-plane octahedral rotations, leading to the absence of superconductivity—highlighting a key difference between trilayer and bilayer systems. [3] reports the observation of a superconducting onset temperature of 50–70 K in oxygen-deficient nickelate thin films grown on highly reduced SrTiO₃ substrates, accompanied by a paramagnetic Meissner effect and superconducting diode effect, attributed to the synergistic interaction between the film and substrate. [4] utilizes RIXS to observe plasmon excitations for the first time in low-valence nickelate Pr₄Ni₃O₈, where strong damping and low propagation velocity reveal unique charge screening behavior, providing quantitative constraints for analogies between nickelate and cuprate superconductors. [5] systematically evaluates the delafossite structure as a competing phase of infinite-layer oxides through high-throughput first-principles calculations, identifying the La-Ni combination as the optimal thermodynamic choice and offering guidance for stabilizing the infinite-layer phase via hole doping. These works advance the understanding of nickelate superconductivity mechanisms and materials design from multiple perspectives, including symmetry, strain engineering, interface effects, electronic excitations, and phase stability. arXiv submission processing window: 2026-06-23 00:00 to 2026-06-23 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-06-23