针对双层镍酸盐La₃Ni₂O₇在常压下的非常规磁序，本文提出了一个忠实反映其晶体对称性的微观哈密顿量。通过大规模密度矩阵重正化群计算表明，在较大的Hund耦合JH作用下，由于隐藏的准一维性，模型中出现了(π/2,π/2)自旋条纹序，并在一定电子浓度范围内持续存在。在更对称的高压区域，当层间反铁磁耦合J⊥足够强时，模型表现出增强的层间配对倾向。该研究揭示了对角自旋条纹的微观起源，并确认Hund耦合JH和层间耦合J⊥是控制La₃Ni₂O₇磁序和配对倾向的关键要素。
4 条关联记录
1 条关联记录
The recent discovery of superconductivity in pressurized bilayer nickelate La3Ni2O7 has triggered tremendous research interest. However, the experimentally observed oxygen deficiency implies that obtaining perfect stoichiometric single crystals is still challenging. The influence of oxygen deficiency on physical properties remains unexplained. Here, we construct a chemical potential phase diagram to characterize the stability of La3Ni2O7. The narrow stable region explains the difficulty of synthesizing pure samples. First, oxygen defect studies reveal that the interlayer apical oxygen vacancy has the highest defect concentrations and is responsible for oxygen deficiency. Second, unfolding band structures show as the oxygen-deficient variant increases, Ni $$3d_{\;z^{2}}$$bands shift toward a lower energy position under the Fermi level at Γ point, which is adverse to the metallization of Ni $$3d_{\;z^{2}}$$bands. Third, high-pressure calculations indicate that oxygen vacancy would destroy the hybridization of interlayer Ni $$3d_{\;z^{2}}$$orbitals, and the larger the oxygen deficiency, the higher the pressure needed to metalize the Ni $$3d_{\;z^{2}}$$bands. Thus, the oxygen deficiency would suppress the emergence of superconductivity in La3Ni2O7−δ. Our results elucidate the mechanism of oxygen deficiency for superconductivity in La3Ni2O7−δ and provide instructive guidance to the experimental research.
3 条关联记录
15 条关联记录
10 条关联记录
本研究通过氧同位素替换（¹⁶O→¹⁸O），利用电阻率和μ子自旋旋转（μSR）实验，系统探索了双层Ruddlesden-Popper镍酸盐La₃Ni₂O₇中电荷密度波（CDW）和自旋密度波（SDW）转变的同位素效应。电阻率测量显示，CDW转变温度在¹⁸O取代后显著升高约6 K，而μSR结果则表明SDW转变温度在实验误差范围内不受影响。拉曼光谱证实了同位素替换的有效性及晶格声子模的软化。这一对比鲜明的同位素响应表明，晶格振动（即电子-声子耦合）在CDW序的形成中扮演重要角色，而SDW序主要源于电子相互作用。研究结果揭示了两种密度波序的不同微观起源，并提示电子-声子耦合可能对Ruddlesden-Popper镍酸盐的超导配对机制具有潜在关联，为理论模型提供了关键约束。
1 条关联记录
3 条关联记录