超 kagome 磁体 Yb₃Sc₂Ga₃O₁₂ 中的晶体电场激发与有效自旋-1/2 基态二重态
Crystal electric field excitations and an effective-spin-$1/2$ ground doublet in the hyperkagome magnet Yb$_3$Sc$_2$Ga$_3$O$_{12}$
- Rice University（莱斯大学）
- Oak Ridge National Laboratory（橡树岭国家实验室）
- National Cheng Kung University（国立成功大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
研究利用非弹性中子散射确定超 kagome 磁体 Yb₃Sc₂Ga₃O₁₂ 的晶体电场激发，得到有效 J_eff=1/2 自由度，修正了之前的能级方案，为构建有效交换哈密顿量提供微观基础。
AI中文摘要：
我们利用非弹性中子散射（INS）确定了稀土超 kagome 磁体 Yb₃Sc₂Ga₃O₁₂ 中 Yb³⁺ 的晶体电场（CEF）激发。观测到三个几乎无色散的磁激发，分别位于 58、68 和 74 meV 附近，对应从基态 Kramer 二重态到 J=7/2 多重态的三个激发二重态的跃迁。受局部 222（D₂）对称性约束的 Stevens 算子分析重现了激发能和谱权重，并得到了 Ising 型基态 g 张量。第一激发二重态位于基态上方约 58 meV 处，在与集体磁性相关的低温范围内建立了一个隔离良好的有效 J_eff=1/2 自由度。值得注意的是，直接测量的 CEF 光谱大幅修正了之前从体测量推断出的能级方案，同时保留了基本的低能赝自旋描述。尽管单个 CEF 参数不具有唯一性，但两种独立的拟合方案给出了一致的激发能、基态二重态波函数和 g 张量。所得的单离子模型还重现了特定热容中特征的磁化率、磁化强度以及 Schottky 异常的磁场演化。这些结果为构建有效交换哈密顿量以及解释 Yb₃Sc₂Ga₃O₁₂ 低能集体激发的未来测量建立了所需的微观单离子基础。
英文摘要：
We use inelastic neutron scattering (INS) to determine the crystal electric field (CEF) excitations of Yb$^{3+}$ in the rare-earth hyperkagome magnet Yb$_3$Sc$_2$Ga$_3$O$_{12}$. Three nearly dispersionless magnetic excitations are observed near 58, 68, and 74~meV, corresponding to transitions from the ground-state Kramers doublet to the three excited doublets of the $J=7/2$ multiplet. A Stevens-operator analysis constrained by the local $222$ ($D_2$) symmetry reproduces the excitation energies and spectral weights and yields an Ising-type ground-state $g$ tensor. The first excited doublet lies approximately 58~meV above the ground state, establishing a well-isolated effective $J_{\mathrm{eff}}=1/2$ degree of freedom over the low-temperature regime relevant to collective magnetism. Notably, the directly measured CEF spectrum substantially revises the level scheme previously inferred from bulk measurements, while preserving the essential low-energy pseudospin description. Two independent fitting protocols give consistent excitation energies, ground-doublet wave functions, and $g$ tensors, despite the nonuniqueness of the individual CEF parameters. The resulting single-ion model also reproduces the characteristic susceptibility, magnetization, and field evolution of the Schottky anomaly in specific heat. These results establish the microscopic single-ion basis needed to construct an effective exchange Hamiltonian and to interpret future measurements of low-energy collective excitations in Yb$_3$Sc$_2$Ga$_3$O$_{12}$.
