发表机构
Johns Hopkins University; University of Tokyo; National High Magnetic Field Laboratory; Florida AM University（约翰斯·霍普金斯大学; 东京大学; 国家高磁场实验室; 佛罗里达农工大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
通过磁拉曼光谱研究Pr$_2$Zr$_2$O$_7$在[111]磁场下的晶场激发，发现kagome面磁矩涨落而非静态极化，解释了磁化降低，支持偶极-四极性质。
AI 中文摘要
烧绿石 Pr$_2$Zr$_2$O$_7$ 的奇异磁性质由自旋、轨道和晶格自由度的耦合决定。该材料中的磁性源于非 Kramers 的 Pr$^{3+}$ 离子，其奇异行为已在磁矩的偶极-四极性质以及无序分裂非 Kramers 双重态的框架下进行了讨论。我们使用磁拉曼光谱探测 Pr$^{3+}$ 在 2 K 温度下、沿 [100] 和 [111] 晶向施加高达 14 T 磁场时的晶场（CEF）激发。对于 $\mathrm{B}\parallel[100]$，拉曼活性晶场模式随磁场的变化可由 Pr$^{3+}$ 基态双重态的常规塞曼分裂定量描述，包括在升高温度下热布居的上塞曼支。对于 $\mathrm{B}\parallel[111]$，光谱分离为三角和 kagome 子晶格的响应，三角晶格上 Pr$^{3+}$ 的 CEF 激发表现出与完全磁矩极化一致的预期塞曼位移。相反，kagome 晶格上 Pr$^{3+}$ 的 CEF 激发并未按预期分裂，而是随磁场增强而显著展宽。这种行为与静态极化构型不一致，可由运动窄化描述唯象地捕捉，其中 kagome 面矩在塞曼分裂能级之间以 meV 时间尺度涨落。这一结果为 $\mathrm{B}\parallel[111]$ 方向观察到的磁化强度降低提供了自然解释，并进一步证明了磁矩的偶极-四极性质。它凸显了拉曼散射作为探测阻挫磁体中奇异自旋-轨道动力学的灵敏探针。
英文摘要
The exotic magnetic properties of the pyrochlore Pr$_2$Zr$_2$O$_7$ are determined by the coupling of spin, orbital, and lattice degrees of freedom. Magnetism in this material originates from the non-Kramers Pr$^{3+}$ ion, and the exotic behavior has been discussed both in the framework of dipole-quadrupole properties of magnetic moments and disorder splitting the non-Kramers doublet. We use magneto-Raman spectroscopy to probe the crystal electric field (CEF) excitations of Pr$^{3+}$ in magnetic fields up to 14 T applied along the [100] and [111] crystallographic directions at 2 K. For $\mathrm{B}\parallel[100]$, the field evolution of the Raman active crystal field modes is quantitatively described by conventional Zeeman splitting of the Pr$^{3+}$ ground state doublet, including the thermally populated upper Zeeman branch at elevated temperature. For $\mathrm{}{B}\parallel[111]$, the spectra separate into responses from the triangular and kagome sublattices, and the CEF excitations of Pr$^{3+}$ on the triangular lattice exhibit the expected Zeeman shift consistent with full moments polarization. In contrast, the CEF excitations of Pr$^{3+}$ on the kagome lattice do not split as expected and instead broaden strongly with increasing field. This behavior is inconsistent with a static polarized configuration and is captured phenomenologically by a motional-narrowing description in which the kagome plane moments fluctuate between Zeeman-split levels on a meV timescale. This result offers a natural explanation for the reduced magnetization observed in $\mathrm{}{B}\parallel[111]$ and provides further evidence of the dipole-quadrupole properties of magnetic moments. It highlights Raman scattering as a sensitive probe of exotic spin-orbital dynamics in frustrated magnets.
