来源 自动抓取
作者 Y. Shen, W. He, J. Sears, Xuefei Guo, Xiangpeng Luo, A. Roll, J. Li, J. Pelliciari, Xi He, I. Bozovic, Junjie Zhang, J. F. Mitchell, V. Bisogni, M. Mitrano, S. Johnston, M. P. M. Dean
arXiv / 出版方 http://arxiv.org/abs/2601.12160v1
PDF https://arxiv.org/pdf/2601.12160v1
相关度评分 4.943
主分类 cond-mat.str-el
发布日期 2026-06-16
研究范式 实验研究
样品形态 单晶

摘要

使用共振非弹性X射线散射（RIXS）在氧K边观测到低化合价镍酸盐Pr4Ni3O8中的等离激元集体激发，并与过掺杂铜氧化物La2-xSrxCuO4进行对比。实验发现，镍酸盐的等离激元在面内动量下表现出色散行为，但相较铜氧化物具有更低的速度和更强烈的阻尼，且在更小的动量下即被过度阻尼而消失。随机相位近似（RPA）计算表明，这种差异源于镍酸盐中减少的电子跳跃和增强的长程库仑相互作用屏蔽效应，面内跳跃积分和库仑相互作用强度均显著小于铜氧化物。此外，镍酸盐的面外等离激元未显示可分辨的色散，可能与其三层耦合结构有关。温度依赖研究发现，Pr4Ni3O8的等离激元随温度升高而软化，而铜氧化物中能量几乎不变但阻尼增大，暗示镍酸盐中可能存在条纹涨落等额外关联。这些结果揭示了镍酸盐中独特的电荷屏蔽景观，电子跳跃减弱和库仑屏蔽增强是区别于铜氧化物的关键特征，可能解释了镍酸盐超导转变温度低于铜氧化物的原因，为两类材料间的类比提供了定量实验约束。

材料

方法

关键词

  • plasmons
  • charge dynamics
  • screened coulomb interactions
  • electron hopping
  • stripe fluctuations

亮点

  • Our findings establish reduced electronic hopping and smaller, more strongly screened, long-range Coulomb interactions as defining features differentiating low-valence nickelates from cuprates.
  • These results may explain the lower superconducting transition temperature of low-valence nickelates compared to cuprates.

结论

  • The nickelate plasmons are more heavily damped and have a lower velocity than those in a cuprate at comparable doping.
  • The plasmons in Pr4Ni3O8 soften with increasing temperature, in contrast to the cuprate where they remain at nearly fixed energy but become more strongly damped.
  • Reduced electronic hopping and enhanced screening of long-range Coulomb interactions are attributed as the cause.

主要论断

  • Plasmons in Pr4Ni3O8 have lower velocity and are more heavily damped than in overdoped La2-xSrxCuO4, disappearing at smaller momenta.
    • 证据: Abstract: 'The experiments revealed that the nickelate plasmons exhibit dispersive behavior… but with significantly lower velocity and stronger damping than the cuprate'
  • RPA calculations attribute these differences to reduced electronic hopping and enhanced long-range Coulomb interaction screening in the nickelate.
    • 证据: Abstract: 'Random phase approximation calculations indicate that these differences originate from reduced electron hopping and enhanced long-range Coulomb interaction screening'

研究流程

  • Sample synthesis
    • 材料: Pr4Ni3O8 single crystals; La2-xSrxCuO4 thin films
    • 方法: High-pressure optical floating zone method; Topotactic reduction in H2/Ar; Atomic-layer-by-layer MBE for cuprate
    • 观察: High-quality crystals with Ni valence state ~+1.33
  • RIXS measurements — Plasmons in nickelates are more heavily damped and have lower velocity than in cuprates
    • 材料: Pr4Ni3O8 and La2-xSrxCuO4
    • 方法: O K-edge resonant inelastic X-ray scattering; Polarization analysis
    • 观察: Well-defined dispersive plasmons below 1 eV; Nickelate plasmons have lower velocity and stronger damping
  • Theoretical modeling — Differences originate from reduced electron hopping and enhanced Coulomb screening
    • 材料: Experimental plasmon dispersion
    • 方法: Random phase approximation (RPA) calculations; Single-layer and trilayer models
    • 观察: Reduced in-plane hopping and long-range Coulomb interaction in nickelate