Paper

Daily Overview: Today’s research highlight focuses on phonon-mode-selective tuning of magnetism and superconductivity in trilayer nickelates. By combining ab initio calculations with the functional renormalization group, the study identifies an out-of-plane oxygen breathing mode with pronounced electron-phonon coupling and constructs a symmetry-resolved, layer-dependent coupling form. The relative phase among the three layers induces distinct retarded electron interactions, which in turn mode-selectively enhance or suppress spin-density-wave order and s±-wave superconductivity. The core mechanism involves screening-mediated spin-phonon interactions acting across energy scales: electron-phonon coupling first modifies high-energy charge screening, then reshapes low-energy magnetic fluctuations, and ultimately affects pairing. This work also reports a negative isotope coefficient for the magnetic state, in qualitative agreement with experiments, providing a microscopic framework for understanding isotope effects in trilayer nickelates and interlayer-phonon tuning of electronic ordered states. arXiv submission processing window: 2026-09-16 00:00 to 2026-09-16 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-09-16

Daily Overview: Today’s highlighted work focuses on the real-space correlation between superconductivity and magnetism in infinite-layer nickelate Nd1−xEuxNiO2 (x = 0.25) films. [1] Scanning SQUID microscopy was used to image the local superfluid density and magnetic structure of an optimally doped sample grown by molecular beam epitaxy on an LSAT substrate, revealing the coexistence of superconductivity and a weak magnetic texture, as well as a highly spatially inhomogeneous superconducting state. Near the superconducting transition, a robust stripe-like superconducting enhancement emerges, accompanied by halo-like defect responses and paramagnetic regions between stripes. These results primarily attribute the anomalous broadening of the superconducting transition to competing magnetic phases and suggest that understanding this stripe-like superconducting enhancement mechanism may provide a new avenue for raising the superconducting temperature of infinite-layer nickelates. arXiv submission processing window: 2026-09-15 00:00 to 2026-09-15 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-09-15

Daily Overview: Today’s highlighted work focuses on an in-depth understanding of the electronic structure of mixed-type Ruddlesden-Popper nickelates, in which the normal-state transport behavior of trilayer Ruddlesden-Popper nickelates provides new clues for the physics of nickelate superconductivity. [1] Based on magnetoconductance quantum corrections in single crystals of Pr4Ni3O10 and La4Ni3O10, negative magnetoresistance and two-dimensional weak-localization signatures were observed at low temperatures, and the magnetoresistance scales with the perpendicular component of the magnetic field, indicating that in-plane transport lies in the quantum diffusion regime while out-of-plane transport is incoherent, and that the electronic ground state is approximately a quasi-two-dimensional disordered Fermi liquid. The weak localization remains relatively robust under a strong spin-orbit and magnetic background, arising from the partial cancellation between spin-orbit scattering and spin-flip scattering and from the spatial isolation of rare-earth ions from the NiO2 layers; pressurizing to 3 GPa continuously suppresses this feature, suggesting a two-dimensional/three-dimensional dimensional crossover and establishing a transport link between the ambient-pressure normal state and the pressure-induced superconducting state. Although these results are not direct superconducting measurements, they are of great significance for understanding the quasi-two-dimensional normal state, disorder effects, and pressure-tuned superconductivity in nickelates. arXiv submission processing window: 2026-09-14 00:00 to 2026-09-14 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-09-14

Daily Overview: Today’s research highlight focuses on the competition between out-of-plane s-wave superconductivity and the out-of-plane bond-order phase (z-BOP) instability in bilayer nickelates, both simultaneously driven by the interlayer spin exchange J⊥. Based on a controlled large-N expansion of the Hubbard-operator path integral, this work studies the strongly correlated single-orbital d_{x^2-y^2} bilayer t-J⊥-V model at the mean-field and beyond-mean-field levels to describe pressurized and thin-film bilayer nickelates. Its central conclusion is that the complex z-BOP gap is dominated by its imaginary part, which endows the interlayer hopping with a complex phase, thereby generating an interlayer current and inducing an in-plane current, and forming a time-reversal-symmetry-breaking loop-current state. This loop-current phase competes with superconductivity, yielding a doping-dependent dome-shaped superconducting region, with optimal superconductivity appearing near the z-BOP quantum critical point. The phase diagram encompasses a pure loop-current phase, a low-doping loop-current–superconductivity coexistence phase, a higher-doping pure superconducting phase, and a correlated metallic state, while the Coulomb interaction has little effect on the formation and stability of the loop current. This strong-coupling single-orbital picture not only provides new insights into nickelate physics but may also inspire quantum simulations of spontaneous loop-current many-body models on platforms such as optical lattices and superconducting quantum circuits. arXiv submission processing window: 2026-09-11 00:00 to 2026-09-11 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-09-11

Daily Overview: The highlighted work today focuses on the anisotropy of the superconducting state, low-energy vortex behavior, and competing density-wave order in Ruddlesden–Popper nickelates. In [1], the authors simultaneously measured the resistance and diamagnetism of (La,Pr)3Ni2O7 thin films and mapped the vortex melting phase diagram under in-plane and out-of-plane magnetic fields. They found that for H ∥ c, geometric confinement gives rise to pancake vortices, and that the anisotropy of the vortex melting field approaches 1 with decreasing temperature, indicating the formation of a nearly isotropic vortex solid and a nearly isotropic superfluid response. This is incompatible with a strictly two-dimensional Ni 3d_{x^2-y^2} band picture, but can be naturally explained by a substantial interlayer superfluid weight supplied by the Ni 3d_{z^2}-derived γ band, providing thermodynamic evidence that superconductivity in bilayer nickelates includes a contribution from the γ band. In [2], 139La NQR studies show that under pressure the spin-density wave and charge-density wave in La4Ni3O10 are intertwined: short-range density-wave order emerges at about 150 K and develops into long-range density-wave order at 139 K, while pressure suppresses the short-range and long-range orders at about 1 K/GPa and 10 K/GPa, respectively, indicating that the long-range order is suppressed more rapidly and competes with superconductivity. This result highlights that the coupling between density-wave order and unconventional superconductivity in trilayer nickelates differs from that in La3Ni2O7. From the perspectives of vortex thermodynamics and local spin/charge order, respectively, these two studies deepen the understanding of superconducting pairing and competing orders in nickelates. arXiv submission processing window: 2026-09-09 00:00 to 2026-09-09 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-09-09