Paper

Daily Overview: Today’s highlighted work focuses on an in-depth understanding of electron correlations, phase fluctuations, and experimental characterization methods in nickel-based superconductors. In [1], RIXS studies on La$_{3-x}$Sr$_x$Ni$_2$O$_7$ thin films reveal that double-stripe spin excitations remain robust within the superconducting dome but collapse sharply in the overdoped non-superconducting regime, directly establishing a link between magnetism and superconductivity. In [2], nano-patterning enhances phase fluctuations in Nd$_{0.8}$Sr$_{0.2}$NiO$_2$, leading to the observation of a two-stage superconducting transition, an anomalous metallic state, and an anisotropy reversal of the in-plane/out-of-plane critical fields, highlighting the potential of phase coherence engineering in strongly correlated systems. In [3], addressing the controversial estimation of the superconducting shielding volume fraction in pressurized Ruddlesden-Popper nickelates, it is clarified that the self-consistent method based on demagnetization factor correction is the standard and correct approach, while the linear assumption of the opposing party leads to an underestimation of the shielding fraction. These works advance the understanding of the mechanism and characterization of nickel-based superconductivity from the perspectives of spin excitations, quantum phase effects, and measurement methodology, respectively. arXiv submission processing window: 2026-03-03 00:00 to 2026-03-03 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-03-03

Daily Overview: Today’s highlights focus on deepening the understanding of the electronic structure of hybrid Ruddlesden-Popper nickelates and clarifying experimental controversies surrounding their superconducting phase fraction. In directly related studies, [1] proposes a triplon-mediated pairing mechanism based on a model of coexisting d_{x^2-y^2} conduction bands and localized d_{3z^2-r^2} spins in bilayer nickelates, which naturally explains the larger superconducting gap in the α band and its significant gap anisotropy, providing microscopic theoretical support for superconductivity in bilayer nickelates. Meanwhile, [2] rigorously addresses methodological controversies in calculating the superconducting phase fraction of La₂SmNi₂O₇ single crystals. Through experimental confirmation of background signals, correction of demagnetization effects, and multi-point characterization, it validates the correctness of the approximately 62.1% superconducting phase fraction reported in the original Nature paper, thereby clarifying previous doubts about the uniformity and phase content of nickelate superconductor single crystals. These two works advance research in the field of nickel-based superconductivity from both theoretical mechanisms and experimental verification. arXiv submission processing window: 2026-03-02 00:00 to 2026-03-02 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-03-02

Daily Overview: Today’s highlight work focuses on an in-depth understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. On one hand, [1] identified triple calculation errors in the zero-field-cooled magnetization data of the high-pressure nickelate superconductor La₂SmNi₂O₇ single crystals, emphasizing that the superconducting phase fraction should be 22.8% instead of the previously reported 62.1%, and warned about the misleading influence of the selection of demagnetization factor and magnetization mode on the estimation of volume fraction, though the authors acknowledge the experimental confirmation of bulk superconductivity. On the other hand, [2] starting from an itinerant perspective, based on tight-binding fitting and random phase approximation analysis of compressively strained bilayer nickel oxide thin films, revealed the decisive role of Hund coupling strength on superconducting pairing symmetry and spin density wave type — under strong Hund coupling, s-wave superconductivity and (π/2,π/2) spin density wave dominate, while weak Hund coupling tends to d-wave pairing and (π,π) spin density wave, qualitatively consistent with density matrix renormalization group results. These two works advance the understanding of the superconducting phase and magnetism in nickelates from the perspectives of data correction and theoretical mechanism, respectively. arXiv submission processing window: 2026-02-27 00:00 to 2026-02-27 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-02-27

Daily Overview: Today’s highlights focus on deepening the understanding of the electronic structure of hybrid Ruddlesden-Popper nickelates. [1] Through theoretical predictions, several cobalt-based La₃Ni₂O₇ analogs (such as LaTh₂Co₂O₇, etc.) have been proposed, in which the cobalt 3d orbitals exhibit half-filled occupancy and strong Hund coupling akin to those in nickelates, with local magnetic moments falling precisely within the optimal window for nickel-based superconductivity. This suggests the possibility of realizing s-wave superconductivity via spin fluctuation mechanisms, providing a theoretical basis for expanding the nickelate superconductor family to cobalt-based systems. [2] In contrast, [2] raises significant doubts about the previously reported method for calculating the superconducting volume fraction in pressurized Ruddlesden-Popper nickelates (e.g., La₄Ni₃O₁₀). It finds that the nonstandard equations used earlier, due to geometric parameter errors, led to nearly twofold overestimations. After correction, the actual superconducting phase fraction is only 51%–59%. This finding necessitates a re-evaluation of all published superconducting volume fraction data for this system. arXiv submission processing window: 2026-02-26 00:00 to 2026-02-26 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-02-26

Daily Overview: Today’s highlights focus on an in-depth understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. In [1], first-principles simulations reveal a precise correspondence between the enhancement of electronic correlation strength driven by structural phase transitions and the superconducting dome in La₃Ni₂O₇, clarifying the key role of A-site cations in the pressure-tuned evolution of correlations. In [2], random phase approximation analysis from an itinerant electron perspective shows that the strength of Hund’s coupling determines the competition between superconducting pairing symmetry (s-wave or d-wave) and magnetic ordering wave vectors ((π/2, π/2) or (π, π)) in the bilayer nickelate system, providing crucial theoretical support for understanding the unconventional mechanism of nickelate superconductivity. arXiv submission processing window: 2026-02-25 00:00 to 2026-02-25 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-02-25