Lattice-Charge Coupling in a Trilayer Nickelate with Intertwined Density Wave Order

摘要

Lattice-Charge Coupling in a Trilayer Nickelate with Intertwined Density Wave Order

材料

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方法

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关键词

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亮点

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结论

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主要论断

• No phonon softening is observed at the CDW wave vector in trilayer nickelate Pr₄Ni₃O₁₀, contrasting with cuprates.
  • 证据: Using inelastic x-ray scattering, we mapped the low-energy phonon dispersions in RE₄Ni₃O₁₀ and found no evidence of softening near the CDW wave vector over a wide temperature range
• The spin degree of freedom, not lattice-charge coupling, is the primary driver of the intertwined density wave order.
  • 证据: Calculations of the electronic susceptibility revealed a peak at the observed SDW ordering vector but not at the CDW wave vector,Our experimental and theoretical findings highlight the crucial role of the spin degree of freedom

研究流程

• crystal growth — High-quality single crystals were synthesized for inelastic x-ray scattering experiments.
  • 材料: Pr₆O₁₁; NiO
  • 方法: high-pressure optical floating zone furnace; two-step growth method
  • 观察: single crystals of Pr₄Ni₃O₁₀ obtained
• X-ray diffraction characterization — Charge density wave order is present with a second-order-like transition.
  • 材料: Pr₄Ni₃O₁₀ single crystals
  • 方法: lab-based four-circle x-ray diffractometer; synchrotron XRD at 30 keV
  • 观察: CDW onset at T_CDW ≈ 157.5K; correlation length ≈6 nm along c-axis; critical exponent n ≈ 0.46
• inelastic x-ray scattering (IXS) measurement — No Kohn anomaly or phonon softening occurs at the CDW wave vector in Pr₄Ni₃O₁₀.
  • 材料: polished Pr₄Ni₃O₁₀ crystal (≈150 μm thickness)
  • 方法: IXS at beamline 30-ID-C (HERIX); energy resolution 1.36 meV; measurements at constant momentum transfer
  • 观察: four phonon branches resolved; no phonon softening at CDW wave vector within resolution; phonon dispersions unchanged across T_CDW
• theoretical calculations (phonon DFT and susceptibility) — Spin degree of freedom drives the intertwined order; CDW is not driven by electronic nesting.
  • 材料: computed Pr₄Ni₃O₁₀ structure
  • 方法: phonon density functional theory (phonopy + VASP); susceptibility calculation (WIEN₂K, Fourier spline)
  • 观察: calculated phonon dispersions agree with experiment; susceptibility shows peak at SDW vector (0.61,0.61,0) but no peak at CDW vector; nesting connects electron and hole pockets at SDW vector