来源 自动抓取
作者 Yong-Yue Zong, Shun-Li Yu, Jian-Xin Li
arXiv / 出版方 https://arxiv.org/abs/2605.10101
PDF https://arxiv.org/pdf/2605.10101
相关度评分 5.617
主分类 cond-mat.str-el
发布日期 2026-05-12
研究范式 理论研究
样品形态 未知

摘要

该研究基于双层两轨道Hubbard模型，采用时间依赖变分原理团簇微扰理论（TDVP-CPT）与大尺度密度矩阵重正化群（DMRG）方法，系统探究了La3Ni2O7中电子关联对费米面拓扑与超导配对对称性的影响。TDVP-CPT在包含多达16个物理位点的团簇上计算发现，电子关联驱动了显著的轨道选择性低能谱重构：dz2轨道的谱权重逐渐耗尽，γ能带下沉至费米能级以下，而α和β能带则出现赝隙，最终在强耦合下形成以dx2-y2轨道为主的费米弧。DMRG计算进一步揭示，主导的超导配对关联与该费米面重构一致演化，从弱耦合下的dz2轨道主导的层间自旋单态配对转变为强耦合下的dx2-y2轨道主导的配对，但始终保持s±波对称性。研究表明，γ费米面的消失非但不抑制超导电性，反而标志着关联驱动的配对通道转变，其关键中介机制包括层间反铁磁涨落、Hund耦合与轨道间杂化。

材料

方法

关键词

亮点

  • Large-scale TDVP-CPT calculations on clusters up to 16 physical sites, the largest such study for this system.
  • Correlation-driven pairing channel shift demonstrates that the pairing mechanism is highly regime-dependent, with Hund's coupling and inter-orbital hybridization playing key roles at strong coupling.

结论

  • Electronic correlations drive an orbital-selective reconstruction: the dz2-derived γ band sinks below the Fermi level, pseudogaps open on α and β bands, leading to dx2-y2-dominated Fermi arcs at strong coupling.
  • The dominant superconducting pairing correlations shift from dz2-dominated to dx2-y2-dominated interlayer spin-singlet pairing while retaining s± structure.
  • Disappearance of the γ pocket does not suppress superconductivity; it signals a correlation-driven shift of the pairing channel mediated by interlayer antiferromagnetism, Hund's coupling, and inter-orbital hybridization.

主要论断

  • Electronic correlations drive an orbital-selective reconstruction: d_z2 spectral weight is depleted, γ band sinks below Fermi level, and pseudogaps open on α and β bands, resulting in dx2-y2-dominated Fermi arcs at strong coupling.
    • 证据: TDVP-CPT spectral functions show progressive depletion of d_z2 weight with increasing U; Fermi arcs emerge at U=6.0 eV
  • The leading superconducting correlations transition from d_z2-dominated to dx2-y2-dominated interlayer spin-singlet pairing as correlations increase, while retaining s± structure.
    • 证据: DMRG calculations show pairing correlation exponent K decreases for dx2-y2 and increases for d_z2 with increasing U; interlayer pairing remains algebraic
  • At weak coupling, inter-orbital hybridization drives d_z2 pairing; at strong coupling, both Hund's coupling and inter-orbital hybridization are essential for dx2-y2 pairing.
    • 证据: DMRG with varied J_H and hybridization shows different dependencies in weak and strong coupling regimes; simultaneous suppression of both greatly weakens pairing

研究流程

  • model_definition — Realistic multi-orbital model for La3Ni2O7.
    • 材料: La3Ni2O7 tight-binding parameters from literature
    • 方法: bilayer two-orbital Hubbard model with on-site interactions
    • 观察: model captures orbital-selective correlation effects
  • tdvp_cpt_spectral_calculations — Electronic correlations drive Fermi surface reconstruction.
    • 材料: clusters up to 16 physical sites
    • 方法: time-dependent variational principle based cluster perturbation theory
    • 观察: orbital-selective depletion of d_z2 spectral weight; γ band sinks below Fermi level; pseudogaps on α and β bands
  • dmrg_superconducting_correlations — Leading superconducting correlations shift from d_z2 to dx2-y2 with increasing correlation strength.
    • 材料: L×W lattices (W=2,4)
    • 方法: density matrix renormalization group with bond dimension up to 12000
    • 观察: interlayer pairing correlations decay algebraically; transition from d_z2- to dx2-y2-dominated pairing
  • analysis_of_pairing_mechanism — Microscopic pairing mechanism is regime dependent.
    • 材料: DMRG results with varying J_H and hybridization
    • 方法: systematic variation of interaction parameters
    • 观察: at weak coupling, inter-orbital hybridization drives d_z2 pairing; at strong coupling, both Hund's coupling and hybridization are essential for dx2-y2 pairing