Daily Overview: Today’s highlights focus on gaining deeper, multi-faceted insight into the electronic structure and superconducting mechanism of hybrid Ruddlesden-Popper nickelates. Precise transport measurements on La₃Ni₂O₇ single crystals reveal how pressure reshapes anisotropic charge dynamics by suppressing the density-wave order and triggering a structural phase transition, giving rise at the density-wave phase boundary to zero-resistance superconductivity with an onset temperature reaching 68 K and a strange metal state exhibiting Planckian dissipation over a wide temperature range. In parallel, theoretical studies on La₅Ni₃O₁₁ show that its intercalated La₂NiO₄ layers, driven by correlation effects, order into antiferromagnetic or band-insulating states and are electronically inert, so that the low-energy physics is entirely dominated by the La₃Ni₂O₇ blocks, providing a unified picture for the minimal effective model of such mixed-layer nickelates. Furthermore, first-principles molecular dynamics that incorporate nuclear quantum effects identify a lattice quantum disordered phase in La₃Ni₂O₇ and related systems, and point out that this phase boundary aligns precisely with the transition temperature on the left side of the superconducting dome, revealing the crucial role of lattice quantum many-body effects in unconventional superconductivity. arXiv submission processing window: 2026-07-30 00:00 to 2026-07-30 00:00 UTC.

1. Density-wave phases, anisotropic transport, and Planckian dissipation in single crystals of the superconductor La3Ni2O7

Summary: Using high-quality La₃Ni₂O₇ single crystals, the researchers established a high-precision pressure–temperature phase diagram by accurately measuring in-plane and out-of-plane resistivity. They resolved two density-wave-related anomalies with distinct pressure dependences: the low-temperature anomaly T₁ is initially suppressed and then sharply enhanced after a structural transition at about 10 GPa, while the high-temperature spin-density-wave anomaly T₂ increases monotonically. The pressure-induced structural transition not only raises the resistivity in both directions but also significantly enhances the low-temperature resistivity anisotropy, indicating that the density-wave order profoundly affects charge dynamics. Once pressure completely suppresses the density-wave phase, zero-resistance superconductivity emerges at the phase boundary with an onset temperature up to 68 K, and the normal-state resistivity exhibits a linear temperature dependence over a wide range from just above the superconducting transition to 300 K, with the scattering rate falling within the Planckian limit. These results reveal that pressure reconstructs anisotropic charge transport by tuning the density-wave order, thereby generating a strongly scattering strange-metal state and superconductivity, and establish that density-wave correlations and Planckian dissipation are defining characteristics of La₃Ni₂O₇.

2. Electronically Inactive Intercalated La$_2$NiO$_4$ Layer in Superconducting La$_5$Ni$_3$O$_{11}$

Summary: This study systematically investigates the electronic role of the intercalated La₂NiO₄ (214) layer in the superconducting material La₅Ni₃O₁₁ by combining density functional theory, Wannier tight-binding modeling, and rotationally invariant slave-boson calculations. A two-orbital model is constructed for the embedded 214 layer using realistic electronic parameters extracted from PBE and HSE06 functionals, and its correlated ground-state phase diagram is computed via the slave-boson approach. The results reveal that within realistic ranges of crystal-field splitting and Coulomb interaction, this layer tends to reside in an antiferromagnetic insulating state or a band insulating state rather than a paramagnetic metallic state, with its low-energy spectral weight completely suppressed. Further analysis of a coupled model incorporating the La₃Ni₂O₇ (327) block and the 214 layer shows that interlayer hybridization does not restore any effective density of states originating from the 214 layer near the Fermi level. Consequently, the low-energy electronic structure of La₅Ni₃O₁₁ is dominated by the 327 block, while the intercalated 214 layer remains electronically inert and does not contribute to the formation of the Fermi surface. This finding clarifies the minimal low-energy effective model for this mixed-layer nickelate and offers a unified picture for understanding superconductivity in intercalated Ruddlesden-Popper nickelates.

3. Unconventional superconductivity from lattice quantum disorder

Summary: This study employs first-principles path-integral molecular dynamics to comprehensively incorporate nuclear quantum many-body effects, constructing free energy surfaces and revealing a lattice quantum disordered (LQD) phase in H3S and La3Ni2O7. By comparing classical and quantum phase boundaries, the LQD phase forms a triangular region in the pressure–temperature phase diagram, with its left boundary precisely aligning with the transition temperature of the left flank of the superconducting dome; notably, the maximum temperature Tcmax of the LQD phase coincides with the maximum superconducting Tc, and the isotope effect is accurately captured. These findings demonstrate that superconductivity on the dome’s left flank originates from a transition from a low-symmetry phase to the quantum disordered phase, with the superconducting state residing entirely within the high-symmetry phase, thereby refuting the two-phase interpretation. The research establishes the LQD phase as a unified framework that not only elucidates the critical role of lattice quantum many-body effects in unconventional superconductivity but also opens new pathways for predicting higher-Tc superconductors and explaining anomalous condensed-matter phenomena.