Daily Overview: The highlighted work today focuses on a deeper understanding of the electronic structure of mixed Ruddlesden–Popper nickelates. For the bilayer nickelate (\mathrm{La}3\mathrm{Ni}2\mathrm{O}7), a theoretical study employs single-site dynamical mean-field theory combined with the numerical renormalization group to construct a bilayer Kondo lattice model and analyze its normal-state phase diagram; under the premise of interlayer tunneling (t\perp=0), the model identifies a non-Fermi-liquid critical point that can be tuned by the interlayer spin coupling (J\perp) or hole doping (x), separating a conventional Fermi liquid in the overdoped region from a pseudogap metal in the underdoped region that has small hole pockets, small quasiparticle weight, and large effective mass (the “second Fermi liquid”), with the latter violating the perturbative Luttinger theorem without symmetry breaking or fractionalization. The authors further use an auxiliary-fermion framework to interpret the pseudogap and the auxiliary fermions in the ground-state wave function as spin polarons and show Kondo-like resonance peaks in the DMFT spectral function; after extending the analysis to finite (t\perp), the authors propose that current experimental samples at (x\approx0.5) lie in the overdoped Fermi-liquid region, whereas the pseudogap phase and non-Fermi-liquid criticality may be reached through electron doping—all of which are theoretical model predictions and inferences rather than experimental observations. arXiv submission processing window: 2026-10-22 00:00 to 2026-10-22 00:00 UTC.

1. Pseudogap and Non-Fermi-liquid criticality in double Kondo model for bilayer nickelates

Summary: The study investigates the normal-state phase diagram of the bilayer Kondo lattice model for the bilayer nickelate (\mathrm{La}3\mathrm{Ni}2\mathrm{O}7) using single-site dynamical mean-field theory combined with the numerical renormalization group. At interlayer tunneling (t\perp=0), the authors identify a non-Fermi-liquid critical point tuned by the interlayer spin coupling (J\perp) or hole doping (x), which separates a conventional Fermi liquid in the overdoped region from a pseudogap metal in the underdoped region; the latter is termed the “second Fermi liquid” (sFL), hosts small hole pockets, and violates the perturbative Luttinger theorem without symmetry breaking or fractionalization. This pseudogap metal resembles a heavy Fermi liquid, with a small quasiparticle weight and a large effective mass. The authors also use an auxiliary-fermion framework to analytically describe the pseudogap and the ground-state wavefunction, interpret the auxiliary fermions as spin polarons, and show a Kondo-like resonance peak in the DMFT spectral function. Extending the analysis to finite (t\perp), the authors propose that current experimental samples with (x\approx0.5) lie in the overdoped Fermi-liquid region, and that the pseudogap phase and non-Fermi-liquid criticality may be reached via electron doping.