Itinerant Nature of Spin-Density-Wave Order in Ruddlesden-Popper Nickelates

摘要

本文针对Ruddlesden-Popper镍酸盐中自旋密度波（SDW）序和磁激发的本质，发展了一个统一的巡游电子描述。核心要素是NiO₂多层块的镜面对称结构，它将低能电子态组织成镜偶和镜奇两个扇区。研究表明，镜相反扇区之间的主导带间嵌套驱动了镜选择性的巡游SDW不稳定性，其集体模式自然重现了实验中观察到的类似自旋波的谱。在La₄Ni₃O₁₀中，SDW进一步诱导出次级镜偶电荷密度波，产生交织的自旋和电荷纹理。这些结果证明，多层镍酸盐的磁性本质上是巡游而非局域矩起源，并确立了镜选择性带间SDW序作为这些体系中磁关联的统一组织原则。

材料

• La₃Ni₂O₇
• La₄Ni₃O₁₀

方法

• Hartree-Fock
• Random phase approximation (RPA)
• Linear spin-wave theory
• Tight-binding modeling
• DFT
• RPA
• tight-binding modeling
• Hartree-Fock method

关键词

• mirror selective interband sdw
• itinerant magnetism
• spin wave like spectra
• intertwined spin and charge textures
• spin density wave
• mirror selective interband nesting
• spin wave excitations

亮点

• The same itinerant SDW framework can simultaneously account for the experimentally observed ordering wave vectors, spin textures, and spin-wave-like magnetic excitation spectra.
• The small ordered moments arise directly from Fermi-surface reconstruction within a partially metallic multiband system.
• Establishes mirror-selective interband SDW order as a unifying organizing principle for magnetic correlations in multilayer nickelates.
• Explains that large effective exchange couplings from spin-wave fits do not correspond to microscopic superexchange interactions.
• Demonstrates that small ordered moments arise from Fermi surface reconstruction, not local moments.

结论

• Magnetism in multilayer nickelates is fundamentally itinerant rather than local-moment in origin.
• Mirror-selective interband SDW order is established as a unifying organizing principle for magnetic correlations in these systems.
• For La₄Ni₃O₁₀, the SDW further induces a secondary mirror-even charge density wave, yielding intertwined spin and charge textures.
• Dominant interband nesting between mirror-opposite bands drives a mirror-selective SDW instability.
• The collective modes of the SDW naturally reproduce the experimentally observed spin-wave-like spectra.
• For La₄Ni₃O₁₀, the SDW induces a secondary mirror-even charge density wave, yielding intertwined spin and charge textures.

主要论断

• The dominant magnetic instability in RP nickelates originates from mirror-odd interband scattering between nested Fermi-surface pockets.
  • 证据: Abstract: 'dominant interband nesting between mirror-opposite bands drives a mirror-selective itinerant SDW instability'
• Magnetism in multilayer nickelates is fundamentally itinerant, not local-moment in origin.
  • 证据: Abstract: 'Our results demonstrate that magnetism in multilayer nickelates is fundamentally itinerant rather than local-moment in origin'
• Magnetism in multilayer nickelates is itinerant, driven by mirror-selective interband nesting
  • 证据: From abstract: 'dominant interband nesting between mirror-opposite bands drives a mirror-selective itinerant SDW instability',From abstract: 'magnetism in multilayer nickelates is fundamentally itinerant rather than local-moment in origin'
• Spin-wave-like excitations naturally emerge from itinerant SDW collective modes
  • 证据: From abstract: 'collective modes naturally reproduce the experimentally observed spin-wave-like spectra'

研究流程

• Model construction — Mirror-selective itinerant SDW instability arises from this nesting
  • 材料: La₃Ni₂O₇ and La₄Ni₃O₁₀ crystal structures
  • 方法: Mirror-even and mirror-odd sector classification; Effective low-energy Hamiltonian
  • 观察: Dominant interband nesting between mirror-opposite bands
• Mean-field and RPA calculation — Magnetism is itinerant rather than local-moment in origin
  • 材料: Low-energy band model with residual interactions
  • 方法: Hartree-Fock decoupling; Random phase approximation (RPA)
  • 观察: Collective modes reproduce experimental spin-wave-like spectra; Small ordered moments
• model_construction — Low-energy states organized into mirror sectors
  • 材料: NiO₂ blocks; La₃Ni₂O₇ and La₄Ni₃O₁₀
  • 方法: mirror symmetry classification; tight-binding model
  • 观察: mirror-even and mirror-odd sectors
• self_consistent_hartree_fock_calculation — Mirror-odd interband SDW instability drives small ordered moments
  • 材料: Two-band model with interactions
  • 方法: Hartree-Fock mean-field
  • 观察: SDW order parameter; ordered moments
• rpa_spin_response_computation — Collective modes reproduce experimentally observed spin-wave spectra
  • 材料: HF ground state
  • 方法: RPA for transverse spin response
  • 观察: collective spin excitation spectra; spin-wave-like modes