Paper

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

Daily Overview: Today’s highlights focus on deepening the understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. In [1], the superconducting pairing in bilayer nickelate La₃Ni₂O₇ is revealed to have a hierarchical structure, with the primary pairing originating from the bonding-antibonding splitting of the Ni 3d({z^2}) orbitals, while orbital hybridization redistributes the superconducting correlations to the 3d({x^2-y^2}) channel. The resulting s± state is robust against changes in Fermi surface topology, unifying previously divergent theoretical perspectives. [2] unifies a series of experiments on the superconducting transition temperature of La₃Ni₂O₇ under oxygen stoichiometry, elemental substitution, pressure, and strain modulation, based on an effective d(_{x^2-y^2}) orbital bilayer t-J model. It is found that the Tc behavior resembles that of overdoped cuprates and exhibits particle-hole asymmetry, and it is proposed that electron doping can further enhance Tc. [3] focuses on the trilayer La₄Ni₃O₁₀, employing cluster exact diagonalization to reveal pressure-induced redistribution of oxygen hole states: under ambient pressure, excess holes are localized in the central NiO₂ layer and interlayer O p_z orbitals, while under high pressure they redistribute to the outer layers, emphasizing similarities with bilayer nickelates and proposing possible charge and spin ordered states. arXiv submission processing window: 2026-03-17 00:00 to 2026-03-17 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-03-17

Daily Overview: Today’s highlight work focuses on deepening the understanding of the electronic structure of hybrid Ruddlesden-Popper nickelates. In [1], using the newly discovered nickel-based superconductor La₃Ni₂O₇ as an example, the study reveals the “orbital dimerization” mechanism underlying its first-order structural phase transition. The authors find that standard DFT and LDA+DMFT methods fail to reproduce the abruptness of the phase transition due to neglecting key interatomic correlations. By constructing a many-body effective Hamiltonian involving low-energy active orbitals and performing exact diagonalization, they point out that when the Ni-O-Ni bond angle approaches linearity, the strong antiferromagnetic superexchange interaction between interlayer Ni orbitals forms spin-singlet bonding, leading to a sharp drop in total energy. This generates a new local energy minimum at a specific configuration, coexisting with the tilted configuration, perfectly explaining the first-order phase transition characteristics and the coexistence of high- and low-pressure structures observed in experiments. This mechanism not only alters the lattice bonding properties but also qualitatively changes the low-energy electronic structure (e.g., the emergence of superconductivity). The established DFT plus many-body correction computational framework provides key microscopic insights into understanding the structure-electronic property correlations in ionic materials containing open-shell d/f electrons. arXiv submission processing window: 2026-03-16 00:00 to 2026-03-16 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-03-16

Daily Overview: Today’s highlighted work focuses on a multi-perspective exploration of the superconductivity mechanism and phase diagram evolution in Ruddlesden-Popper phase bilayer nickelates. In [1], a review systematically summarizes the breakthrough progress in achieving ambient-pressure superconductivity in La₃Ni₂O₇ thin films, emphasizing the stabilization of the superconducting phase through epitaxial compressive strain and the controversial ARPES results regarding Fermi surface topology. It points out that weak-coupling theory predicts possible s± or d-wave pairing, but key issues remain unresolved. [2], from a theoretical perspective, proposes an orbital-space bilayer model (OSBM) and predicts that hole-doped reduced La₃Ni₂O₆ may be a new type of superconductor, with a pairing mechanism fundamentally different from that of La₃Ni₂O₇—driven by inter-orbital interactions in the incipient-band scenario, leading to s±-wave superconductivity, thereby opening a new theoretical direction for the nickelate superconductor family. [3] experimentally reveals the universal existence of a superconducting dome in compressively strained bilayer nickelate thin films. Through fine control of oxygen stoichiometry, it is found that strong scattering introduced by oxygen vacancies leads to a granular superconductor-insulator transition without changing the superconducting onset temperature, while interstitial oxygen mainly affects the carrier concentration. This phase diagram feature consistently appears across different rare-earth combinations and alkaline-earth-doped samples, providing key experimental evidence for understanding the relationship between electronic inhomogeneity and the emergence of superconductivity. arXiv submission processing window: 2026-03-13 00:00 to 2026-03-13 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-03-13

Daily Overview: Today’s highlights focus on the in-depth understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. In [1], Zhou et al. achieved a superconducting onset temperature of approximately 63 K in (La,Pr)₃Ni₂O₂ thin films under ambient pressure via giant oxidative atomic layer epitaxy, and found that the superconducting enhancement is closely associated with strange metal behavior (α≈1), with significantly stronger interlayer coupling than that of bismuth-based cuprates. In [2], Wang et al.’s high-field transport study of La₂.₈₂Sr₀.₁₈Ni₂O₇ thin films revealed that the in-plane upper critical field is strongly suppressed by the Pauli paramagnetic limit (approximately 58 T), with an anisotropy ratio γ≈1.34, supporting a three-dimensional bulk superconductivity in this system and highlighting the critical role of spin paramagnetic effects in determining the high-field phase diagram. In [3], Sanchez-Manzano et al. characterized the superconducting dimensionality of infinite-layer Pr₀.₈Sr₀.₂NiO₂ thin films through vortex phase diagrams, discovering a quasi-two-dimensional vortex liquid-to-glass transition at low disorder, while enhanced disorder drives the system into a purely two-dimensional state, establishing disorder strength as a key tuning parameter. These three works collectively reveal the intrinsic relationships among dimensionality, interlayer coupling, and anomalous normal-state behavior in nickel-based superconductivity from the perspectives of superconducting enhancement mechanisms, paramagnetic pair-breaking limits, and vortex dimensionality tuning. arXiv submission processing window: 2026-03-12 00:00 to 2026-03-12 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-03-12