Paper

Daily Overview: Today’s highlight focuses on an in-depth understanding of the electronic structure of hybrid Ruddlesden–Popper nickelates. In Ref. [1], the authors employ DFT + dynamical mean-field theory to systematically investigate the effects of epitaxial strain on the normal-state electronic structure, quasiparticle renormalization, Fermi surface, and magnetic correlations of the bilayer nickelate La₃Ni₂O₇. They find that the Ni 3d bands exhibit pronounced orbital-selective renormalization and strong incoherence, with the x²−y² and 3z²−r² states approaching orbital-selective localization. The electronic properties of this system are highly sensitive to in-plane strain: tensile strain and moderate compressive strain enhance magnetic correlations, whereas at a large compressive strain of approximately −4% a Lifshitz transition occurs, in which the γ Fermi surface sheet associated with the shallow bonding Ni 3z²−r² flat band disappears and the magnetic correlations drop sharply, suggesting that superconductivity may be suppressed. These results support the picture that the spin/charge density wave stripe instability is driven by Fermi surface nesting and indicate that pressure and strain can effectively tune spin–charge density wave order and enhance spin fluctuations. arXiv submission processing window: 2026-08-18 00:00 to 2026-08-18 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-08-18

Daily Overview: Today’s highlighted work focuses on an in-depth understanding of the electronic structure of hybrid Ruddlesden-Popper nickelates. Specifically, Ref. [1] systematically investigated the possibility of electron doping in La₃Ni₂O₇ thin films by substituting lanthanum with tetravalent elements using first-principles density functional theory calculations. The results show that cerium doping is ineffective in introducing electron carriers into the low-energy bands, whereas zirconium, hafnium, and thorium are efficient electron donors. Among them, zirconium and hafnium preferentially inject electrons into the d_{x^2−y^2}-derived band, while thorium injects more electrons into the d_{z^2}-derived band. Electron doping significantly enhances the interlayer hopping t⊥ between d_{z^2} orbitals, which is expected to increase the interlayer superexchange coupling J⊥ and thereby raise the superconducting transition temperature T_c. The study also calculated Coulomb interaction parameters using the constrained random phase approximation and identified candidate dopant elements for achieving electron-doped La₃Ni₂O₇, providing a new platform for enriching the nickelate material family and clarifying its superconducting pairing mechanism. arXiv submission processing window: 2026-08-17 00:00 to 2026-08-17 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-08-17

Daily Overview: Today’s highlight focuses on an in-depth understanding of the interplay among charge, spin, and pairing symmetry in the bilayer nickelate La₃Ni₂O₇. Two studies reveal the rich physics of this system from the perspectives of intrinsic order competition and external field tuning of pairing, respectively. On one hand, self-consistent calculations based on an eight-orbital tight-binding model show that, in the low-pressure orthorhombic phase, a double-stripe spin-density wave forms first and triggers an intertwined charge-density wave at lower temperatures, leading to low-spin states at certain Ni sites. The discovery of this spin–charge hierarchical order provides a key link between the ambient-pressure density-wave phase and the high-pressure superconducting phase. On the other hand, dynamical cluster approximation combined with quantum Monte Carlo simulations indicates that applying a vertical electric field in La₃Ni₂O₇ thin films can effectively tune the interlayer orbital distribution, suppressing the high-temperature dominant s±-wave pairing while significantly enhancing d-wave pairing. In particular, under electron doping, an electric-field-induced pairing symmetry transition may occur, offering new many-body computational evidence for understanding the pairing mechanism of nickel-based superconductivity and its control. arXiv submission processing window: 2026-08-11 00:00 to 2026-08-11 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-08-11

Daily Overview: Today’s highlight focuses on the theoretical identification of the superconducting pairing mechanism in the hybrid Ruddlesden-Popper nickelate La₃Ni₂O₇. Using mirror symmetry, the study proposes an orbital-selective diagonal gap test, demonstrating that a dz2-dominated pairing would introduce nodes along the diagonal direction of the Brillouin zone, contradicting the isotropic nodeless gap observed by ARPES and STM. In contrast, pairing dominated by the dx2-y2 orbital driven by Hund’s rule naturally yields a nodeless gap, consistent with experimental data. Weak-coupling calculations similarly favor dz2 domination, which is thus ruled out. This diagonal gap criterion firmly establishes that the Hund-driven dx2-y2 orbital pairing is the most relevant superconducting mechanism in La₃Ni₂O₇. arXiv submission processing window: 2026-08-06 00:00 to 2026-08-06 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-08-06

Daily Overview: Today’s highlights focus on the experimental verification of the superconducting pairing symmetry in Ruddlesden–Popper nickelates and the theoretical elucidation of the correlation-enhanced mechanism. A team from the University of Science and Technology of China, using angle-resolved photoemission spectroscopy, directly observed for the first time a nodeless superconducting gap opening at the transition temperature in pseudogap-free La₂PrNi₂O₇ thin films. The order parameter is approximately 16 meV, and the corresponding specific-heat jump was extracted, providing the previously missing thermodynamic evidence for the superconducting phase transition in nickelates. They also found no one-to-one correspondence between the γ pocket on the Fermi surface and superconductivity, but that Fermi surface topology and strain effects profoundly influence the emergence of superconductivity. The experiment unambiguously supports s-wave pairing. On the theoretical side, for La₃Ni₂O₇ under high pressure, studies combining dynamical mean-field theory with self-energy renormalized random phase approximation reveal that only when the selective correlation renormalization of the d₃z²−r² orbital is included does the dominant pairing instability reverse from a d-wave channel to a sign-changing s± state. This resolves the ambiguity in the pairing symmetry that plagued bare weak-coupling calculations and highlights the decisive role of strong correlation effects in determining the superconducting pairing symmetry in nickelates. arXiv submission processing window: 2026-08-05 00:00 to 2026-08-05 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-08-05