Paper

Daily Overview: Today’s highlight focuses on deepening the understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. Specifically, Ezra Day-Roberts et al. employed a combined DFT and DMFT approach to systematically compare the electronic structure, magnetism, and correlation effects of infinite-layer nickelate LaNiO₂ under electron and hole doping. They discovered a significant asymmetry: hole doping strongly suppresses the self-doping effect of the rare-earth 5d electron pockets, whereas electron doping enlarges these pockets without effectively hole-doping the Ni-d_{x²-y²} orbitals, leading to markedly different magnetic behaviors—hole doping rapidly suppresses antiferromagnetic order, while under electron doping, the antiferromagnetic state remains the ground state. Despite these pronounced differences, electronic correlations are consistently dominated by the Ni-d_{x²-y²} orbital, indicating that a single-band description can be applied to both doping scenarios. This provides a key theoretical basis for understanding nickelate superconductivity and its analogy with copper oxides. arXiv submission processing window: 2026-06-02 00:00 to 2026-06-02 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-06-02

Daily Overview: Today’s highlight focuses on deepening the understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. In [1], X-ray absorption spectroscopy systematically probed the unoccupied states of infinite-layer La₁₋ₓCaₓNiO₂, revealing that Ni–O covalency undergoes an orbital-selective crossing near the superconducting dome. This crossing coincides with the sign reversal of the Hall coefficient and the decline in superconducting critical temperature, providing key experimental evidence for establishing a unified orbitally resolved phase diagram. [2] used polarized ultrafast spectroscopy to uncover significant electronic nematicity in the normal state of bilayer La₃Ni₂O₇, while the trilayer La₄Ni₃O₁₀ exhibits isotropy, suggesting that the breaking of two-fold rotational symmetry may promote superconducting pairing in bilayer systems. [3] first-principles calculations show that the superconducting transition temperature of freestanding infinite-layer Nd₀.₈₅Sr₀.₁₅NiO₂ films increases monotonically under pressure. The physical origin lies in lattice compression increasing the Ni-3d orbital bandwidth and weakening relative electronic correlations, thereby alleviating the overly strong correlation effects induced by the low valence state of Ni. These three works elucidate the intrinsic relationship among electronic structure, correlation effects, and superconductivity in nickel-based superconductors from different perspectives. arXiv submission processing window: 2026-06-01 00:00 to 2026-06-01 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-06-01

Daily Overview: Today’s highlights focus on breakthrough explorations of electron doping strategies and high-field behavior in nickel-based superconducting systems. In [1], first-principles calculations systematically evaluate the feasibility of electron doping via tetravalent element substitution in bilayer Ruddlesden–Popper La₃Ni₂O₇ thin films, clearly indicating that zirconium, hafnium, and thorium can effectively introduce electron carriers and enhance the interlayer hopping of the Ni d_{z²} orbital, potentially raising the superconducting transition temperature and providing key candidate doping pathways to clarify the pairing mechanism debate. Meanwhile, in [2], a high-field-stabilized reentrant superconducting state with a transition temperature up to 40 K is observed in infinite-layer nickelate thin films. The phase diagram can be perfectly fitted by the Jaccarino-Peter field compensation mechanism, indicating that the internal exchange field provided by the introduced Eu²⁺ ions effectively suppresses Pauli paramagnetic pair breaking. This marks the first realization of such strong-field-stabilized superconductivity in high-temperature superconductors, opening new directions for exploring superconducting applications under extreme magnetic fields. arXiv submission processing window: 2026-05-29 00:00 to 2026-05-29 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-05-29

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