Paper

Daily Overview: Today’s highlighted work focuses on deepening the understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. In [1], a theoretical study based on first-principles and fluctuation exchange approximation (FLEX) systematically analyzed the crystal structure, electronic structure, and superconducting pairing properties of La₃Ni₂O₇ thin films on different substrates (LSAT, LAO, SLAO). By constructing a two-orbital bilayer Hubbard model with the inclusion of +U corrections, it was found that although the electronic structure (e.g., the presence or absence of the γ-pocket) depends on the crystal structure and computational details, the s±-wave pairing symmetry remains robust, and this robustness originates from pairing mediated by finite-energy spin fluctuations, which is insensitive to the Fermi surface topology. However, the observation that the superconducting transition temperature of the thin films (~40 K) is halved compared to that of the pressurized bulk (~80 K) can only be explained by models employing a small interlayer hopping integral (|t⊥|) derived from the experimental crystal structure, revealing the critical influence of lattice structure on Tc. This work provides an important theoretical perspective for understanding the relationship between structure and superconductivity in nickel-based superconducting thin films. arXiv submission processing window: 2026-05-27 00:00 to 2026-05-27 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-05-27

Daily Overview: Today’s highlights focus on an in-depth understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. [1] High-pressure high-temperature spectroscopy reveals the correlation between the disappearance of structural tilting and the metallicity transition in La₃Ni₂O₇, showing that the high-symmetry untilted phase, although accompanied by superconductivity, is not a sufficient condition. [2] Using a two-orbital model and DMRG calculations, it is clarified that the (π/2, π/2) spin stripe under ambient pressure originates from the synergy of Hund coupling and interlayer antiferromagnetic coupling in quasi-one-dimensional zigzag chains, and it is indicated that this model can enhance interlayer pairing in the high-pressure phase. Meanwhile, [3] focusing on the relationship between superconducting pairing and the filling of the 3d_{z²} orbital, numerical results suggest that the itinerancy of this orbital favors superconductivity, while charge order competes with it. In the field of infinite-layer nickelates, [4] based on first-principles and FLEX analysis, it is pointed out that pressure alleviates excessive electron correlation, thereby enhancing spin fluctuations, which is the key mechanism for the T_c enhancement in freestanding Nd₀.₈₅Sr₀.₁₅NiO₂ films. These works collectively advance the understanding of the microscopic origins of nickel-based superconductivity. arXiv submission processing window: 2026-05-26 00:00 to 2026-05-26 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-05-26

Daily Overview: Today’s highlights focus on the multidimensional exploration of Ruddlesden-Popper-type nickelate superconductivity. An experimental study successfully prepared Pr$_3$Ni$_2$O$_7$ thin films through epitaxial stabilization and observed superconductivity under high pressure, with an onset transition temperature as high as 66 K. It was also found that the critical pressure required for superconductivity increases with decreasing rare-earth ion radius, providing a new pathway for expanding the bilayer nickelate superconductor family. On the other hand, theoretical calculations reveal that electron doping can universally enhance $s^\pm$-wave pairing superconductivity in La$_3$Ni$_2$O$_7$, and propose heterojunctions as a feasible experimental realization approach, where interorbital synergy is key to the instability of two-orbital cooperative superconductivity. Additionally, at the methodological level, a study combined DFT+U with the finite displacement method to systematically evaluate the impact of Hubbard corrections on electron-phonon interactions in the infinite-layer nickelate LaNiO$_2$, finding that the coupling strength is insufficient to explain the experimentally observed superconducting temperature, highlighting the critical roles of Fermi surface topology and correlation effects on electron-phonon coupling. arXiv submission processing window: 2026-05-21 00:00 to 2026-05-21 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-05-21

Daily Overview: Today’s highlights focus on an in-depth understanding of the electronic structure and magnetic order of mixed Ruddlesden-Popper nickelates, revealing a new pathway to achieving bulk superconductivity. In [1], theoretical studies show that hole doping of the bilayer nickelate La₃Ni₂O₇ under ambient pressure induces nearly perfect Fermi surface nesting, significantly enhancing antiferromagnetic spin fluctuations and raising the superconducting transition temperature to experimentally observable levels, providing a feasible route to bulk superconductivity without the need for high pressure or strain. In [2], spin-polarized scanning tunneling microscopy was used to image the stripe order in the trilayer nickelate La₄Ni₃O₁₀ in real space, revealing that its periodicity and gap characteristics are highly similar to those of cuprate high-temperature superconductors. For the first time, atomic-scale stripe dynamics triggered by tunneling electrons were observed, offering key clues for understanding the pairing mechanism in nickel-based superconductors. In [3], a unified itinerant description framework was developed for the magnetic nature of spin density wave order in RP nickelates, indicating that the magnetism in La₃Ni₂O₇ and La₄Ni₃O₁₀ arises from mirror-selective interband scattering rather than local magnetic moments, thereby revising the traditional understanding of effective exchange interactions. arXiv submission processing window: 2026-05-20 00:00 to 2026-05-20 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-05-20

Daily Overview: Today’s highlights focus on deepening the understanding of the electronic structure of hybrid Ruddlesden-Popper nickelates. [1] Based on a bilayer t-J model, the modulation of superconducting transition temperature by oxygen stoichiometry, elemental substitution, pressure, and strain in La₃Ni₂O₇ is explained in a unified manner, indicating that electron doping is a potential route to enhance Tc. [2] High-precision transport measurements reveal the critical role of interlayer electronic coherence in Ruddlesden-Popper nickelates: stronger interlayer coherence favors superconductivity, and the out-of-plane resistivity serves as a sensitive probe of magnetic and density-wave orders, providing strict constraints on the microscopic mechanism of superconductivity. [3] Combining first-principles calculations with dynamical cluster quantum Monte Carlo simulations, it is predicted that electron doping can universally enhance s±-wave superconductivity in La₃Ni₂O₇, with heterostructure systems exhibiting the highest Tc in the underdoped regime, and revealing a cooperative pairing mechanism between dz² and dx²-y² orbitals. arXiv submission processing window: 2026-05-19 00:00 to 2026-05-19 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-05-19