Electronic structure, quasiparticle renormalizations, and magnetic correlations in the alternating single-layer bilayer nickelate La₅Ni₃O₁₁

摘要

本研究采用DFT+DMFT方法，系统探讨了交替单层-双层Ruddlesden-Popper型镍酸盐La₅Ni₃O₁₁（1212-LNO）在正常态的电子结构和磁相关性。结果表明，结构上不同的单层和双层Ni离子表现出显著差异：双层Ni离子中的e_g态形成了强烈重整化的准粒子能带，其中Ni的x²-y²和3z²-r²轨道有效质量增强因子分别达到约3.5和4.2；而单层Ni离子的e_g态则呈现轨道选择莫特绝缘态，其中Ni的3z²-r²轨道具有窄能隙，x²-y²轨道则表现为金属性且强非相干（非费米液体）行为。磁相关分析表明，双层NiO₆板中可能形成自旋与电荷密度波交织的条纹，主要不稳定性对应波矢Q=(1/3,1/3)的“上-下-0”自旋图案，并与(1/4,1/4)的“上-上-下-下”双列条纹态竞争。单层Ni的3d电子则倾向于形成奈尔型磁序。在压力下，1212-LNO经历轨道选择莫特绝缘体-金属相变，伴随单层Ni e_g态的金属化，其近费米能级处呈现强非相干的非费米液体行为。总体而言，关联效应显著重构了磁相关性，使其从DFT预测的单层主导转变为双层主导，强调了层间约束和轨道依赖关联的关键作用。

材料

• La₅Ni₃O₁₁ (1212-LNO)

方法

• DFT+DMFT

关键词

• orbital selective mott transition
• magnetic correlations
• spin stripes
• non fermi liquid
• confinement effects

亮点

• Correlation effects cause a crossover from monolayer-dominated (in DFT) to bilayer-dominated magnetic correlations.
• Emergent flat-band behavior of bilayer Ni states near the Fermi level.

结论

• Bilayer Ni ions form strongly renormalized quasiparticle bands with mass enhancement factors ≈3.5 and 4.2 for dx2-y2 and d3z2-r2 orbitals, while monolayer Ni ions show an orbital-selective Mott insulating state.
• Magnetic correlations are dominated by bilayer Ni states with stripe instabilities at wave vectors (1/3,1/3) and (1/4,1/4).
• Under pressure, an orbital-selective Mott insulator-metal transition occurs, with monolayer Ni exhibiting non-Fermi-liquid behavior.

主要论断

• The e_g states of bilayer Ni ions form strongly renormalized quasiparticle bands with mass enhancement factors of approximately 3.5 and 4.2 for the Ni dx2-y2 and d_z2 orbitals, respectively.
  • 证据: the e_g states of bilayer Ni ions form strongly renormalized quasiparticle bands, with effective mass enhancement factors of approximately 3.5 and 4.2 for the Ni x²-y² and 3z²-r² orbitals
• The e_g states of monolayer Ni ions exhibit an orbital-selective Mott insulating state, where the Ni 3d_z2 orbital has a narrow gap and the 3dx2-y2 orbital displays metallic but strongly incoherent (non-Fermi-liquid) behavior.
  • 证据: the e_g states of monolayer Ni ions exhibit an orbital-selective Mott insulating state, where the Ni 3z²-r² orbital possesses a narrow gap and the x²-y² orbital displays metallic but strongly incoherent (non-Fermi liquid) behavior.
• Magnetic correlation analysis indicates intertwined spin and charge density wave stripes in the bilayer NiO₆ planes, with the primary instability corresponding to an 'up-down-0' spin pattern at Q=(1/3,1/3) competing with a 'up-up-down-down' double-stripe state at (1/4,1/4).
  • 证据: Magnetic correlation analysis indicates that intertwined spin and charge density wave stripes may form in the bilayer NiO₆ planes, with the primary instability corresponding to an “up-down-0” spin pattern at wave vector Q=(1/3,1/3) competing with a “up-up-down-down” double-stripe state at (1/4,1/4).

研究流程

• DFT+DMFT calculation for electronic structure — Electronic states show layer- and orbital-dependent correlations.
  • 材料: La₅Ni₃O₁₁ (1212-LNO)
  • 方法: DFT+DMFT with continuous-time quantum Monte Carlo
  • 观察: qualitative differences between monolayer and bilayer Ni ions; bilayer Ni: strongly renormalized quasiparticle bands with mass enhancement factors 3.5 (dx2-y2) and 4.2 (d_z2); monolayer Ni: orbital-selective Mott insulating state, d_z2 has narrow gap, dx2-y2 metallic but incoherent (non-Fermi-liquid)
• analysis of magnetic correlations — Magnetic correlations are dominated by bilayer NiO₆ block with intertwined spin and charge density wave stripes.
  • 材料: 1212-LNO
  • 方法: static magnetic susceptibility from DMFT Green's function
  • 观察: leading instability: bilayer NiO₆ block with wave vector (1/3,1/3) corresponding to 'up-down-0' spin pattern; competing instability: (1/4,1/4) corresponding to 'up-up-down-down' double-stripe state; monolayer Ni: Néel-type order
• pressure study — Under pressure, 1212-LNO undergoes an orbital-selective Mott insulator-metal transition in the monolayer, but bilayer magnetic correlations dominate.
  • 材料: 1212-LNO at 30 GPa
  • 方法: DFT+DMFT
  • 观察: Mott insulator-metal transition in monolayer Ni; monolayer Ni states show non-Fermi-liquid behavior with strongly incoherent spectral weight; bilayer Ni quasiparticle renormalizations reduced; magnetic correlations similar to ambient pressure