Pressure induced redistribution of oxygen hole states in La₄Ni₃O₁₀

摘要

本文采用密度泛函计算与包含局域交换和库仑相互作用的多轨道、多原子团簇精确对角化方法，通过最小Ni₃O₁₄团簇研究了三层镍氧化物La₄Ni₃O₁₀的局域低能电子态。研究发现，在常压下，三个Ni名义上均为+2价，其中两个额外空穴中的一个局域于中心NiO₂层，与dx²-y²轨道形成张-赖斯单态；另一个空穴主要占据两层间O p_z轨道的反键组合，并与三个NiO₂层的dz²轨道形成的面外三自旋极化子杂化。由此，面内自旋取向交替由外层dx²-y²轨道承载，层间呈反铁磁关联，同时中心层绝缘且磁矩可忽略。在高压下，两个额外空穴分别集中于一个外层和内层，各自形成dx²-y²轨道的张-赖斯单态或面内三自旋极化子。团簇结果提示的可能电荷与自旋有序态突出了双层La₃Ni₂O₇与三层La₄Ni₃O₁₀之间的相似性。

材料

• La₄Ni₃O₁₀

方法

• DFT
• Multi-orbital cluster exact diagonalization
• Wannier projections
• Ni₃O₁₄ cluster model

关键词

• zhang rice singlet
• three spin polaron
• oxygen hole states
• spin density wave
• charge density wave
• intertwined order

亮点

• The study reveals pressure-induced redistribution of oxygen hole states in La₄Ni₃O₁₀.
• It provides insights into the interplay between structure and electronic correlations in trilayer nickelates.

结论

• At ambient pressure, one extra hole localizes in the central NiO₂ layer forming a Zhang-Rice singlet with dx2-y2 orbital, while the other hole occupies the antibonding combination of interlayer O pz orbitals hybridizing with a three-spin polaron.
• At high pressure, the two extra holes concentrate on outer and inner layers separately forming Zhang-Rice singlets or in-plane three-spin polarons.
• The central layer becomes insulating with negligible magnetic moment.
• Possible charge and spin ordered states highlight similarities between bilayer La₃Ni₂O₇ and trilayer La₄Ni₃O₁₀.

主要论断

• At ambient pressure, one extra hole localizes in the central NiO₂ layer forming a Zhang-Rice singlet with dx2-y2 orbital.
  • 证据: Abstract,Full text: At ambient pressure, one of the two extra holes is localized in the central NiO₂ layer forming a Zhang-Rice singlet with dx2-y2 orbital.
• At high pressure, the two extra holes concentrate on one outer layer and the inner layer, forming ZRS or in-plane 3SP.
  • 证据: Abstract,Full text: At high pressure, the two extra holes are concentrated on one of two outer layers and the inner layer separately forming the ZRS with dx2-y2 orbitals or in-plane 3SP.
• The pressure-induced redistribution of oxygen hole states results in different magnetic and electronic properties.
  • 证据: Abstract,Full text: At ambient pressure, in-plane spin orientation alternation is carried by outer dx2-y2 orbitals with interlayer AFM correlation; central layer is insulating.

研究流程

• DFT_calculation
  • 材料: La₄Ni₃O₁₀
  • 方法: VASP; Wien2K; maximally localized Wannier functions
• cluster_ED_calculation
  • 方法: exact diagonalization of Ni₃O₁₄ cluster; multi-orbital Hamiltonian
  • 观察: dominant configurations and weights
• state_analysis
  • 方法: spin state analysis; weight distribution
  • 观察: pressure-induced redistribution of oxygen hole states
• interpretation — At ambient pressure, one hole forms a Zhang-Rice singlet in central layer; at high pressure, holes redistribute to outer layers.