标题： Weyl半金属\textit{R}AlSi（\textit{R} = 铈，镨和钕）中的晶体电场激发 显示英文标题

标题： Crystalline electric field excitations in Weyl semimetal \textit{R}AlSi (\textit{R} = Ce, Pr and Nd)

摘要： 稀土金属间化合物系统\textit{R}Al\textit{X} (\textit{R} = 稀土元素, \textit{X} = Si 和 Ge) 被认为是磁性外尔半金属的有前途的候选材料。 由于稀土元素与周围原子之间的复杂相互作用，以及与巡游电子的杂化，这一家族可能具有高度有趣和新颖的磁结构，因此表现出动态行为。 我们结合非弹性中子散射（INS）、比热和磁化率测量系统地研究了\textit{R}AlSi (\textit{R} = La, Ce, Pr 和 Nd) 的多晶样品。 INS 测量在 CeAlSi 中识别出分辨良好的晶体电场（CEF）激发，在 19.2 和 24.9 meV 处，在 PrAlSi 中在 5.4 meV 处，在 NdAlSi 中在 2.5 和 4.2 meV 处。 我们使用相应的CEF模型分析了INS数据，并确定了\textit{R}AlSi（\textit{R} = Ce, Pr和Nd）的CEF参数和基态波函数。 我们的结果表明它们的基态具有强烈的单离子各向异性： $|\pm3/2\rangle$（94.5%）在CeAlSi中，$|\pm3\rangle$（99.2%）在PrAlSi中，以及 $|\pm9/2\rangle$（76.2%）在NdAlSi中。 值得注意的是，NdAlSi中的较弱各向异性和强交换相互作用促进了低温下的竞争磁序和CEF分裂，这与CeAlSi和PrAlSi磁态中的稳健CEF水平形成对比。 显示英文摘要

摘要： The rare earth intermetallic system \textit{R}Al\textit{X} (\textit{R} = rare earth elements, \textit{X} = Si and Ge) is known to be a promising candidate of magnetic Weyl semimetal. Due to the complex interactions between the rare earth elements and surrounding atoms, as well as hybridization with itinerant electrons, this family likely possesses highly intriguing and novel magnetic structures and thus exhibits dynamic behaviors. We systematically probe polycrystalline samples of \textit{R}AlSi (\textit{R} = La, Ce, Pr and Nd) combining inelastic neutron scattering (INS), heat capacity and magnetic susceptibility measurements. The INS measurements identify well-resolved crystalline electric field (CEF) excitations at 19.2 and 24.9 meV in CeAlSi, at 5.4 meV in PrAlSi, and at 2.5 and 4.2 meV in NdAlSi. We analyzed the INS data using the corresponding CEF models and determined the CEF parameters and ground state wave functions of \textit{R}AlSi (\textit{R} = Ce, Pr and Nd). Our results suggest strong single-ion anisotropy in their ground states: $|\pm3/2\rangle$ (94.5\%) in CeAlSi, $|\pm3\rangle$ (99.2\%) in PrAlSi, and $|\pm9/2\rangle$ (76.2\%) in NdAlSi. Notably, the weaker anisotropy and strong exchange interactions in NdAlSi promote competing magnetic orders and CEF splitting at low temperature, contrasting with the robust CEF levels in magnetic states of CeAlSi and PrAlSi.