来源 自动抓取
作者 Jing-Yu Zhao, Ya-Hui Zhang
arXiv / 出版方 https://arxiv.org/abs/2603.25742
PDF https://arxiv.org/pdf/2603.25742
相关度评分 5.110
主分类 cond-mat.str-el
发布日期 2026-03-27
研究范式 理论研究
样品形态 未知

摘要

该研究利用单站点动力学平均场理论（DMFT）对双层近藤晶格模型进行了系统研究，旨在探索双层镍酸盐正常态的相图。当层间隧穿不存在时，研究发现了由层间自旋耦合或空穴掺杂调谐的非费米液体临界点，该临界点将过掺杂区的标准费米液体与欠掺杂区的赝能隙金属分隔开来。这一赝能隙相被称为“第二费米液体”，其特征为具有小空穴口袋且违反微扰Luttinger定理，但不存在对称性破缺或分数化现象，其行为类似于重费米液体，准粒子残留小、有效质量大。研究还基于ancilla费米子框架提供了赝能隙和基态波函数的直观解析描述，将ancilla费米子解释为自旋极化子，并在DMFT计算中直接展示了该复合费米子的Kondo共振峰。将该分析扩展到有限层间隧穿情形后，研究应用于双层镍酸盐La3Ni2O7，提出当前实验样品（x≈0.5）处于过掺杂费米液体区域，而通过电子掺杂可能进入赝能隙相和非费米液体临界区，这为理解该类材料中的异常金属行为提供了理论预测。

材料

方法

关键词

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

亮点

  • 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.

结论

  • 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.

主要论断

  • A non-Fermi-liquid critical point separates a standard Fermi liquid in the overdoped region from a pseudogap metal (sFL) in the underdoped regime.
    • 证据: 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.
    • 证据: 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.
    • 证据: 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.

研究流程

  • model_setup
    • 材料: bilayer nickelate model
    • 方法: double Kondo lattice model; bilayer Hubbard model
  • DMFT_NRG_simulation
    • 方法: single-site DMFT with NRG impurity solver
    • 观察: self-consistent Green's functions; phase diagram
  • phase_diagram_analysis
    • 方法: topological index from Wilson chain; bosonic susceptibility
    • 观察: NFL critical point; two distinct FL phases (FL and sFL)
  • spectral_function_analysis
    • 方法: momentum-resolved spectral function from DMFT self-energy
    • 观察: 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.
    • 方法: ancilla fermion framework