Source capture
Authors Jing-Yu Zhao, Ya-Hui Zhang
arXiv / Publisher https://arxiv.org/abs/2603.25742
PDF https://arxiv.org/pdf/2603.25742
Relevance score 5.110
Primary category cond-mat.str-el
Published 2026-03-27
Research paradigm Theoretical
Sample form Unknown

Summary

This study systematically investigates the bilayer Kondo lattice model using single-site dynamical mean-field theory (DMFT) to explore the phase diagram of the normal state of bilayer nickelates. In the absence of interlayer tunneling, a non-Fermi-liquid critical point tuned by interlayer spin coupling or hole doping is identified, separating the standard Fermi liquid in the overdoped region from a pseudogap metal in the underdoped region. This pseudogap phase, termed the "second Fermi liquid," is characterized by small hole pockets and violates the perturbative Luttinger theorem, yet exhibits no symmetry breaking or fractionalization; its behavior resembles that of a heavy Fermi liquid with small quasiparticle residues and large effective masses. Furthermore, an intuitive analytical description of the pseudogap and ground-state wavefunction is provided within the ancilla fermion framework, where the ancilla fermion is interpreted as a spin polaron, and the Kondo resonance peak of this composite fermion is directly shown in DMFT calculations. Extending the analysis to finite interlayer tunneling, the study applies the results to the bilayer nickelate La3Ni2O7, proposing that current experimental samples (x≈0.5) lie in the overdoped Fermi liquid region, while electron doping may drive the system into the pseudogap phase and the non-Fermi-liquid critical regime, offering theoretical predictions for understanding anomalous metallic behavior in such materials.

Materials

Methods

Keywords

  • non fermi liquid criticality
  • pseudogap
  • bilayer kondo lattice
  • second fermi liquid
  • heavy fermi liquid
  • luttinger theorem violation

Highlights

  • Provides a theoretical framework for understanding pseudogap and strange metal behavior in bilayer nickelates.
  • Uses ancilla fermion interpretation as a spin polaron.
  • Predicts that electron doping can access the pseudogap phase.

Conclusions

  • A non-Fermi-liquid critical point separates a standard Fermi liquid in the overdoped region from a pseudogap metal in the underdoped regime.
  • The pseudogap phase (second Fermi liquid) exhibits small hole pockets and violates the perturbative Luttinger theorem without symmetry breaking.
  • The pseudogap phase behaves like a heavy Fermi liquid with small quasiparticle residue and large effective mass.
  • Current experimental samples (x≈0.5) reside in the overdoped FL regime, suggesting pseudogap and NFL criticality may be accessed via electron doping.

Main claims

  • A non-Fermi-liquid critical point separates a standard Fermi liquid in the overdoped region from a pseudogap metal (sFL) in the underdoped regime.
    • Evidence: Abstract,Full text: we identify a non-Fermi-liquid critical point tuned by J⊥ or x, which separates a standard FL in the overdoped region from a distinct PG metal in the underdoped regime.
  • The sFL phase exhibits small hole pockets and violates the perturbative Luttinger theorem despite no symmetry breaking or fractionalization.
    • Evidence: Abstract,Full text: This PG phase… exhibits small hole pockets and violates the perturbative Luttinger theorem despite the absence of symmetry breaking or fractionalization.
  • Current experimental samples (x≈0.5) reside in the overdoped FL regime; electron doping may access the pseudogap phase and NFL criticality.
    • Evidence: Abstract,Full text: We propose that current experimental samples (x ≈ 0.5) reside in the overdoped FL regime, suggesting that the pseudogap phase and the NFL criticality may be accessed via electron doping.

Workflow

  • model_setup
    • Materials: bilayer nickelate model
    • Methods: double Kondo lattice model; bilayer Hubbard model
  • DMFT_NRG_simulation
    • Methods: single-site DMFT with NRG impurity solver
    • Observations: self-consistent Green's functions; phase diagram
  • phase_diagram_analysis
    • Methods: topological index from Wilson chain; bosonic susceptibility
    • Observations: NFL critical point; two distinct FL phases (FL and sFL)
  • spectral_function_analysis
    • Methods: momentum-resolved spectral function from DMFT self-energy
    • Observations: pseudogap in sFL; small hole pockets
  • interpretation — sFL phase is a heavy Fermi liquid with small quasiparticle residue; NFL criticality may explain strange metal behavior in bilayer nickelates.
    • Methods: ancilla fermion framework