发表机构
Università di Parma; Brown University; Università di Bologna; Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche; University of California Santa Barbara（帕尔马大学; 布朗大学; 博洛尼亚大学; 意大利国家研究委员会材料工坊研究所; 加州大学圣塔芭芭拉分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究结合NQR测量与DFT计算，揭示CsV₃Sb₅中Sn取代诱导局域结构畸变，在x=1时稳定两种近简并V三聚体结构，明确了Sn取代对钒基kagome化合物结构与电子相的复杂影响。
AI 中文摘要
理解化学取代对 kagome 金属竞争相的影响，对于厘清局域结构畸变与电子不稳定性之间的相互作用至关重要。在CsV₃Sb₅（简称CVS）中，Sn取代会强烈改变电子相图，但驱动这一现象的微观机制仍不清楚。本研究结合¹²¹Sb核四极共振（NQR）测量与密度泛函理论计算，探究CsV₃Sb₅₋ₓSnₓ中Sn取代的原子尺度效应。在低Sn浓度下，观测到的NQR卫星峰呈现Sn取代诱导的局域结构畸变特征，与计算分析定性一致。这些杂质诱导的特征在整个实验研究的掺杂范围（直至x=0.65）内持续存在，且在室温下仍可观测。对于完全掺杂的理想情况x=1，kagome晶格的动力学不稳定性估算表明，两种能量近简并的平衡结构会稳定存在，其特征为V三聚体，沿c轴相邻层间存在零或π相移。综上，这些结果表明，Sn取代在钒基kagome化合物中驱动了局域杂质诱导畸变与竞争结构不稳定性之间的复杂相互作用。
英文摘要
Understanding the effect of chemical substitution on competing phases of kagome metals is crucial for disentangling the interplay between local structural distortions and electronic instabilities. In \cvs, Sn substitution strongly modifies the electronic phase diagram, yet the microscopic mechanism driving this remains unclear. Here, we combine $^{121}$Sb nuclear quadrupole resonance (NQR) measurements and density functional theory calculations to investigate the atomic-scale effects of Sn substitution in CsV$_3$Sb$_{5-x}$Sn$_x$. At low Sn concentrations, the observed satellite NQR peaks exhibit signatures of local structural distortion induced by Sn substitution, qualitatively consistent with our computational analysis. These impurity-induced features persist across the entire experimentally investigated doping range, up to $x$ = 0.65, and remain observable up to room temperature. For $x=1$, the fully doped idealized case, the estimated dynamical instabilities of the kagome lattice suggest the stabilization of two nearly energy-degenerate equilibrium structures characterized by V-trimers, distinguished by a zero- or $π$-phase shift between adjacent layers along the $c$-axis. Together, these results show that Sn substitution drives a complex interplay between local impurity-induced distortions and competing structural instabilities in vanadium-based kagome compounds.
