Daily Overview: The highlight of today’s work focuses on an in-depth understanding of the electronic structure of mixed Ruddlesden-Popper nickelates. In [1], DFT and RPA calculations revealed an s±-wave pairing mechanism in the bilayer subsystem of high-pressure La₅Ni₃O₁₁, where the monolayer subsystem is coupled to the bilayer via weak interlayer Josephson coupling, naturally explaining the dome-shaped Tc-pressure relationship and highlighting the distinct pressure response of mixed-phase compared to pure-phase nickelates. [2] proposes that applying a perpendicular electric field in La₃Ni₂O₇ single-double layer thin films can drive charge transfer, increasing the filling rate and thereby enhancing intralayer d-wave pairing, with theoretical predictions that Tc could exceed the liquid nitrogen temperature (~77 K), providing a new pathway for achieving high-temperature superconductivity at ambient pressure. [3] systematically constructs the superconducting phase diagram of multilayer square-planar nickelates Nd_{n+1}Ni_nO_{2n+2} (n = 4–8), achieving a maximum onset Tc of 12.9 K (n = 6), with magnetic fluctuations persisting in the superconducting region and the superconducting regime overlapping with that of infinite-layer nickelates, offering a template for atomic-precision layered design. [4] points out that in pressurized Ruddlesden-Popper nickelates, the incorrect formula used has systematically overestimated the superconducting volume fraction by approximately a factor of two (actual value only 51–59%), calling for recalculation using the correct equation, thus providing an important correction to the reliability of related experimental data. arXiv submission processing window: 2026-02-24 00:00 to 2026-02-24 00:00 UTC.

1. Pairing mechanism and superconductivity in pressurized La$_5$Ni$_3$O$_{11}$

Summary: Using density functional theory (DFT) and random phase approximation (RPA) calculations, this study systematically analyzes the electronic properties and superconducting mechanism of La₅Ni₃O₁₁ under high pressure. DFT band structures reveal that this material, characterized by alternating stacks of bilayer and monolayer NiO₂ planes, exhibits two nearly decoupled subbands originating from the bilayer and monolayer subsystems, respectively. RPA analysis indicates that superconducting pairing predominantly occurs within the bilayer subsystem, displaying an s±-wave pairing symmetry similar to that in pressurized La₃Ni₂O₇, while the monolayer subsystem primarily serves as a bridge connecting adjacent bilayers via extremely weak interlayer Josephson coupling (IJC) to achieve phase coherence along the c-axis. Under low pressure, increasing pressure significantly enhances IJC, thereby raising the bulk superconducting transition temperature (Tc); at sufficiently high pressures, the reduced density of states at the γ-pocket leads to a gradual decrease in Tc. This mechanism naturally explains the experimentally observed dome-shaped Tc-pressure dependence and reveals the distinct pressure response of mixed-phase compared to pure-phase nickelate superconductors.

2. Possible Liquid-Nitrogen-Temperature Superconductivity Driven by Perpendicular Electric Field in the Single-Bilayer Film of La$_3$Ni$_2$O$_7$ at Ambient Pressure

Summary: Given the urgent need to enhance the superconducting transition temperature (Tc) of La₃Ni₂O₇ single- and double-layer thin films under ambient pressure, this study proposes applying a vertical electric field to drive charge transfer for superconductivity enhancement. The vertical field drives electrons from higher-potential layers to lower-potential layers; since the Ni 3d_{z²} orbital is nearly half-filled and cannot accommodate additional electrons, the inflowing electrons primarily fill the 3d_{x²-y²} orbitals of the lower-potential layer, thereby increasing its filling rate. Using a simplified single-orbital model and a comprehensive two-orbital model, combined with slave-boson mean-field theory and density matrix renormalization group methods, numerical calculations reveal that the increased filling suppresses interlayer s-wave pairing but strongly enhances intralayer d-wave pairing, causing the bottom-layer-dominated d-wave superconductivity to rise rapidly. When the interlayer voltage reaches approximately 0.1–0.2 V, Tc can surpass the liquid nitrogen temperature (around 77 K), achieving high-temperature superconductivity in the liquid nitrogen temperature range under ambient pressure. This approach requires no high pressure and avoids chemical doping disorder, providing a feasible route to realize high-Tc superconductivity in La₃Ni₂O₇ ultrathin films, which warrants further experimental verification.

3. Superconducting phase diagram of multi-layer square-planar nickelates

  • Relevance Score: 5.3755
  • Authors: Grace A. Pan, Dan Ferenc Segedin, Sophia F. R. TenHuisen, Lopa Bhatt, Harrison LaBollita, Abigail Y. Jiang, Qi Song, Ari B. Turkiewicz, Denitsa R. Baykusheva, Abhishek Nag, Stefano Agrestini, Ke-Jin Zhou, Jonathan Pelliciari, Valentina Bisogni, Hua Zhou, Mark P. M. Dean, Hanjong Paik, David A. Muller, Lena F. Kourkoutis, Charles M. Brooks, Matteo Mitrano, Antia S. Botana, Berit H. Goodge, Julia A. Mundy
  • Affiliations: Cornell University, Max Planck Institute for Chemical Physics of Solids, Harvard University, Arizona State University, Brookhaven National Laboratory, Diamond Light Source, Argonne National Laboratory
  • Link: https://arxiv.org/abs/2602.19093
  • Paper page: Superconducting phase diagram of multi-layer square-planar nickelates

Summary: This study systematically constructs the superconducting phase diagram of multilayer square-planar nickelates Nd_{n+1}Ni_nO_{2n+2} (n = 4–8), revealing that compounds with n = 4 to 7 exhibit signs of superconductivity, with a maximum onset critical temperature of 12.9 K (n = 6), while n = 8 shows only weak superconducting correlations. As the layer number n decreases, the superconducting anisotropy undergoes a reversal due to the effect of 4f electrons at the neodymium sites—the electronic structure approaches that of cuprates, and magnetic fluctuations persist in both the superconducting region and the overdoped nonsuperconducting region. Notably, this superconducting region overlaps with that of chemically doped infinite-layer nickelates, highlighting commonalities and differences among different structural realizations in square-planar nickelates. This work establishes a general template for synthesizing novel nickel-based superconductors through atomic-precision layered design.

4. Nearly twofold overestimation of the superconducting volume fraction in pressurized Ruddlesden-Popper nickelates

Summary: Regarding the zero-field-cooled DC diamagnetic response reported by Zhu et al. in pressurized La₄Ni₃O₁₀, which yielded a superconducting volume fraction of 81–86% via calculation, the present authors recalculated using the same raw experimental data and standard magnetic susceptibility procedures and found the actual fraction to be only 51–59%. Upon requesting detailed calculation equations, the authors noted that the new equation (Equation 3) employed by Zhu et al. to compute the superconducting volume fraction has never appeared in the literature and contains a fundamental error. Through magnetic moment simulations of samples A and B, each assumed to contain 50% superconducting phase, the authors demonstrate that this equation erroneously outputs a volume fraction close to 100%, leading to an overestimation of approximately twofold. This error not only affects the single sample in Zhu et al.’s study but also pervades all currently reported superconducting volume fractions for Ruddlesden–Popper nickelates. Thus, the present paper reveals the source of this systematic overestimation and calls for recalculation using the correct magnetic interaction equation (Equation 7).