Paper

Daily Overview: Today’s highlight focuses on the bosonic phase revealed by the superconductor-insulator transition in infinite-layer nickelate superconductors. By constructing a spatially periodic network structure to regulate the phase coherence of Cooper pairs, this study achieves a superconductor-insulator transition in samarium nickel oxide thin films and observes magnetoresistance oscillations with a period of h/2e, directly confirming the existence of 2e Cooper pairs in nickel oxides. Experiments indicate that the transition is primarily driven by enhanced superconducting fluctuations, and that Cooper pairs dominate charge transport throughout the transition process. The discovery of two anomalous metallic states—observed under finite and zero magnetic fields, respectively—can both be characterized by bosonic excitations, suggesting a key role of vortex dynamics in the ground state. This work establishes nickel oxides as a platform for studying the rich bosonic phases arising from the modulation of Cooper-pair phase coherence. arXiv submission processing window: 2026-02-23 00:00 to 2026-02-23 00:00 UTC. ...

arXiv Daily: nickelate superconductors 2026-02-23

Daily Overview: Today’s highlights focus on deepening the understanding of the electronic structure of mixed Ruddlesden–Popper nickelates. In [1], a superconducting phase diagram was constructed by synthesizing multilayer planar tetragonal nickel oxide thin films (n = 3–8). Superconducting signatures were observed for n = 4 to 8, with the highest superconducting transition temperature of approximately 12.9 K at n = 6. The superconducting anisotropy reversal is attributed to the 4f electron moments at the Nd site, and the electronic structure approaches that of cuprates. Meanwhile, persistent magnetic fluctuations overlap with the superconducting region of infinite-layer nickelates, suggesting a common physical foundation. In [2], a reanalysis of the superconducting volume fraction in pressurized Ruddlesden–Popper nickel oxide (La₄Ni₃O₁₀) was conducted. It points out that the previously reported 81–86% value was overestimated by about a factor of two due to errors in treating the demagnetization factor in the formula derivation, with the actual value being 51–59%. It emphasizes that all related reports must be corrected based on standard magnetostatic formulas. These works provide critical insights into the phase diagram regularities and measurement reliability of nickel-based superconductivity. arXiv submission processing window: 2026-02-22 08:27 to 2026-02-22 17:34 UTC. ...

arXiv Daily: nickelate superconductors 2026-02-22

Daily Overview: Today’s highlights focus on advancing the understanding of the electronic structure of hybrid Ruddlesden-Popper nickelates. [1] By measuring the complete phase diagram of Nd({1-x})Sr(x)NiO(2) thin films via ellipsometry and employing a two-band Drude model, strong correlations and multiband superconducting characteristics were revealed: the spectral weights of the electron and hole bands undergo reconstruction with doping, and at optimal doping, both bands contribute to the superconducting condensation, directly confirming the multiband superconducting nature. [2] Using a neural quantum state method to simulate the mixed-dimensional (t\parallel)-(J\parallel)-(J\perp) model describing high-pressure bilayer nickelate La(_3)Ni(_2)O(_7), direct numerical evidence of ground-state superconductivity was obtained on an 8×8×2 lattice. A crossover from BEC-type pairing under strong interlayer coupling to BCS-type pairing under weak coupling was observed, along with a first-order phase transition from interlayer s-wave to intralayer d-wave pairing symmetry. These two works deepen the understanding of electronic correlations, multiband pairing, and pairing mechanisms in nickel-based superconductors from the perspectives of experimental spectroscopy and theoretical simulation, respectively. arXiv submission processing window: 2026-02-10 09:18 to 2026-02-10 18:55 UTC. ...

arXiv Daily: nickelate superconductors 2026-02-10

Daily Overview: Today’s highlights focus on deepening the understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. In [1], polarization-resolved electronic Raman scattering was employed to probe the density wave state of La₃Ni₂O₇ single crystals, revealing momentum-selective anisotropic electronic correlations and confirming the coexistence of spin density wave gaps with two different coupling strengths, thereby providing a microscopic foundation for understanding the emergence of nickelate superconductivity under pressure. In [2], magnetotransport measurements on compressively strained La₂SmNi₂O₇ thin films directly observed the coexistence of antiferromagnetic spin fluctuations and superconductivity at low temperatures. The unique “Mexican hat”-shaped magnetoresistance behavior reveals a novel relationship between fluctuations and superconductivity, offering key experimental evidence for elucidating the pairing mechanism of nickelate superconductivity. arXiv submission processing window: 2026-02-08 14:41 to 2026-02-08 14:47 UTC. ...

arXiv Daily: nickelate superconductors 2026-02-08

Daily Overview: Today’s highlight focuses on advancing the understanding of the electronic structure of hybrid Ruddlesden-Popper nickelates. Using Raman scattering spectroscopy, the research team comprehensively characterized the electronic, magnetic, and lattice excitations of the bilayer nickelate La₃Ni₂O₇ under ambient pressure. For the first time, they simultaneously observed two types of in-plane spin exchange interactions along the Ni-O bond direction and the diagonal direction in the spin-density-wave state, revealing the bond-diagonal antiferromagnetic competition mediated by the nickel d_{x²-y²} orbitals. Moreover, the discovery of low-energy two-magnon excitations provides direct spectroscopic evidence for spin disproportionation, while anomalous phonon softening hints at an incipient lattice instability. These results collectively establish the correlation among competitive spin interactions, spin disproportionation, and lattice response in this system, providing key experimental foundations for understanding the microscopic mechanism of nickelate superconductivity. arXiv submission processing window: 2026-02-05 06:39 to 2026-02-05 06:39 UTC. ...

arXiv Daily: nickelate superconductors 2026-02-05