Paper

Daily Overview: Today’s highlight work focuses on deepening the understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. In [1], a theoretical study based on a bilayer two-orbital Hubbard model reveals how electron correlations drive orbital-selective Fermi surface reconstruction in La₃Ni₂O₇: the d_{z²} orbital spectral weight is depleted, the γ band sinks below the Fermi level, while the d_{x²-y²} orbital forms Fermi arcs. Concurrently, the superconducting pairing transitions from an interlayer spin singlet dominated by the d_{z²} orbital under weak coupling to a pairing dominated by the d_{x²-y²} orbital under strong coupling, while consistently maintaining s±-wave symmetry. This indicates that the disappearance of the γ Fermi surface does not suppress superconductivity but rather signifies a correlation-driven change in the pairing channel. In [2], through a systematic analysis of strained La₃Ni₂O₇ thin films, it is found that biaxial compressive strain predominantly elongates the outer apical Ni–O bonds, significantly enhancing the Jahn-Teller splitting while hardly affecting interlayer d_{z²} orbital hopping. This identifies Jahn-Teller distortion as a key microscopic parameter for strain-tuned electronic structure and supports its central role in optimizing superconductivity. arXiv submission processing window: 2026-05-12 00:00 to 2026-05-12 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-05-12

Daily Overview: Today’s highlight work focuses on deepening the understanding of the electronic structure of hybrid Ruddlesden-Popper nickelates. In [1], based on a bilayer t-J model of the d_{x²-y²} orbital combined with first-principles parameters, the researchers successfully unified the explanation of various experimental调控 behaviors of Tc in La₃Ni₂O₇ using slave-boson mean-field and density matrix renormalization group methods. The model reveals particle-hole asymmetric doping dependence: hole doping suppresses Tc while electron doping enhances Tc, thereby explaining the “half-dome” behavior in oxygen content regulation and the decrease of Tc caused by calcium/strontium substitution. Additionally, the variation of Tc with interlayer antiferromagnetic superexchange J⊥ naturally describes the “right triangle” relationship under pressure and the enhancement effect of compressive strain. Compared to weak-coupling theory and the d_{z²} orbital mechanism, this work provides a more unified framework and predicts that electron doping without introducing disorder (e.g., substituting lanthanum with higher-valent elements) may further increase Tc. arXiv submission processing window: 2026-05-11 00:00 to 2026-05-11 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-05-11

Daily Overview: No relevant papers have been published in the field of nickel-based superconductivity today. 1. Pair-Breaking and Dimensionality in Spin-Orbit Coupled Superconductors Relevance Score: 4.5787 Authors: Reiley Dorrian, Mizuki Ohno, Elena Williams, Adrian Llanos, Joseph Falson Link: http://arxiv.org/abs/2605.06514v1 Summary: This paper employs the multi-mechanism Kharitonov-Feigel’man (KF) framework to analyze the thickness-dependent superconductivity in spin-orbit-coupled superconducting thin films of LaBi₂, and systematically compares it with the conventional Klemm-Luther-Beasley (KLB) model. A series of high-quality single-crystal films ranging from the “bulk” to the ultrathin limit (2.1 nm) were prepared by molecular beam epitaxy, and the temperature-dependent upper critical fields were measured under parallel magnetic fields. In contrast to the KLB model, which only considers paramagnetic pair-breaking, the KF framework simultaneously incorporates three mechanisms: orbital pair-breaking, paramagnetic effects, and magnetic scattering (spin-exchange scattering). An anomalous enhancement of the critical field was observed in the ultrathin limit (2.1 nm), attributed to the suppression of magnetic fluctuations by the magnetic field, which effectively reduces the spin-exchange scattering rate. Through fitting with the KF model, the contributions of each scattering channel were successfully isolated: the magnetic scattering time is on the order of 10⁻¹²–10⁻¹¹ seconds, while the KLB model, due to its neglect of orbital pair-breaking, severely overestimates the spin-orbit scattering time (by up to four orders of magnitude) at finite thickness and is meaningful only in the zero-thickness limit. The study also reveals differences among three distinct definitions of the zero-field critical temperature (experimental value, KLB extrapolated value, and KF value without magnetic impurities), and emphasizes that the determination of the Pauli limit should be extrapolated to the strictly two-dimensional limit. The results indicate that the KLB model, by ignoring magnetic disorder and orbital effects, introduces systematic biases in the interpretation of fundamental superconducting parameters (such as critical temperature and Pauli limit), whereas the KF framework provides a more accurate deconstruction of pair-breaking mechanisms in two-dimensional superconductors, offering new insights into the relationship between scattering times and superconductivity. ...

arXiv Daily: Nickelate superconductors 2026-05-08

Daily Overview: Today’s highlights focus on deepening the understanding of superconductivity in mixed Ruddlesden-Popper nickelate La₃Ni₂O₇₊δ. Experimentally, [1] successfully synthesized a series of samples containing pure bilayer phase, hybrid phase, and trilayer intergrowth phase through systematic control of oxygen content, identifying distinct superconducting transition temperatures (Tc) corresponding to different phases. A phase diagram of Tc and upper critical field as functions of oxygen content was established, revealing the key regulatory role of oxygen content in superconductivity. Theoretically, [2] provided a unified framework based on the effective d_{x²-y²} orbital bilayer t-J∥-J⊥ model to explain multiple regulatory behaviors of Tc observed in experiments, such as oxygen stoichiometry, alkaline-earth metal substitution, rare-earth element substitution, and pressure effects. This work points out the similarity between this system and hole-overdoped copper oxides and predicts that electron doping could further enhance Tc. Together, these two studies advance the understanding of nickel-based superconductivity pairing mechanisms and material design. arXiv submission processing window: 2026-05-07 00:00 to 2026-05-07 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-05-07

Daily Overview: Today’s highlights focus on an in-depth understanding of the electronic structure of hybrid Ruddlesden-Popper nickelates. In [1], neutron scattering techniques were employed to resolve the spin ordering and dynamics of bilayer nickel oxide La₃Ni₂O₇ single crystals. Clear spin excitations were observed at reciprocal space position Q = (0, 0.5, 2.5), featuring a spin gap of approximately 5 meV and significant in-plane anisotropic dispersion. The out-of-plane modulation directly confirms antiferromagnetic interlayer coupling. Based on linear spin-wave theory, the experimental dispersion can be precisely described as a bilayer Heisenberg model incorporating competing exchange interactions, with the magnetic structure exhibiting stripe-type order. Although the spin-wave bandwidth is only 25% of that in cuprates, the normalized local dynamic magnetic susceptibility is significantly enhanced, and the total fluctuating magnetic moment is comparable to that of cuprates. This reveals that intermediate-energy spin excitations induced by strong electronic correlations are an intrinsic feature of the system, establishing a magnetic framework distinct from cuprates and providing direct evidence for understanding the superconducting pairing mechanism in this system. arXiv submission processing window: 2026-05-06 00:00 to 2026-05-06 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-05-06