Daily Overview: This post sorts papers by relevance to nickelate superconductors. Summaries are AI-generated and may contain errors. arXiv submission processing window: times are unavailable (UTC).

1. Superconductivity in Ruddlesden-Popper nickelates: a review of recent progress, focusing on thin films

Summary: In recent years, significant breakthroughs have been achieved in the study of Ruddlesden-Popper (RP) nickel oxide superconductors. This article systematically reviews the experimental and theoretical progress in this field, with a particular focus on thin-film systems. Key findings include the emergence of superconductivity in bilayer La₃Ni₂O₇ (T_c ~ 80 K) and trilayer La₄Ni₃O₁₀ under high pressure, and, critically, the realization of ambient-pressure superconductivity in ultra-thin films of La₃Ni₂O₇ grown on substrates providing compressive strain—a breakthrough that overcomes the high-pressure limitation and enables the use of experimental techniques previously inaccessible in the superconducting state, such as angle-resolved photoemission spectroscopy (ARPES). On the theoretical side, the system requires simultaneous consideration of both the Ni e_g and a_{1g} orbitals, as well as the strong interlayer coupling within bilayers that gives rise to a “dimer” picture, and exhibits strange metal behavior and strong correlation features reminiscent of cuprates. By comparing the similarities and differences among various RP nickel oxides, this article offers a new perspective on understanding the mechanism of high-temperature superconductivity in correlated electron systems and outlines future research directions.

2. Pairing properties of correlated three-leg ladders with strong interchain couplings near 1/3 filling

Summary: This paper employs the density matrix renormalization group method to study the ground-state properties of a three-leg t-J ladder with strong interchain coupling near 1/3 filling. When holes are doped into the spin-gapped state at 1/3 filling, the pairing correlation function exhibits power-law decay while the spin correlation function decays exponentially; in contrast, electron doping does not significantly enhance pairing correlations. Further comparison with the three-leg Hubbard model shows that the pairing correlation properties of the hole-doped state are similar to those of the t-J model, but require a sufficiently large spin gap. The study indicates that hole doping near 1/3 filling favors superconducting pairing, and this asymmetric pairing property differs from the phase diagram predicted by weak-coupling theory, providing numerical evidence for understanding the electronic properties of tri-layer nickelate superconductors.