We investigate the magnetic and crystal electric field (CEF) states of the Kondo lattice system ${\mathrm{CeCuGa}}_3$ by muon spin relaxation ($\mu \mathrm{SR}$), neutron diffraction, and inelastic neutron scattering (INS) measurements. A noncentrosymmetric ${\mathrm{BaNiSn}}_3$-type tetragonal crystal structure (space group $I4mm$) is inferred from x-ray as well as from neutron powder diffraction. The low-temperature magnetic susceptibility and heat capacity data show an anomaly near 2.3–2.5 K, associated with long-range magnetic ordering, which is further confirmed by $\mu \mathrm{SR}$ and neutron diffraction data. The neutron powder diffraction collected at 1.7 K shows the presence of magnetic Bragg peaks indexed by an incommensurate magnetic propagation vector k $=(0.148,0.148,0)$ and the magnetic structure is best described by a longitudinal spin density wave with ordered moments lying in the $ab$-plane. An analysis of the INS data based on a CEF model reveals the presence of two magnetic excitations near 4.5 meV and 6.9 meV. The magnetic heat capacity data suggest an overall CEF splitting of 20.7 meV, however, the excitation between 20 and 30 meV is very broad and weak in our INS data, but could provide an evidence of CEF level in this energy range in agreement with the magnetic entropy. Our analysis of INS data based on the CEF-phonon model indicates that the two excitations at 4.5 meV and 6.9 meV have their origin in CEF-phonon coupling (i.e., splitting of one CEF peak into two peaks, called vibron), with an overall splitting of 28.16 meV, similar to the case of ${\mathrm{CeCuAl}}_3$ and ${\mathrm{CeAuAl}}_3$.

中文翻译：

---

近藤晶格CeCuGa3中的晶体电场和可能与声子的耦合

我们研究了 Kondo 晶格系统的磁和晶体电场 (CEF) 状态 ${\mathrm{铈铜镓}}_3$ 通过μ子自旋弛豫（$\mu \mathrm{SR}$)、中子衍射和非弹性中子散射 (INS) 测量。非中心对称${\mathrm{镍锡}}_3$-型四方晶体结构（空间群 $\mathrm{一世}4米米$) 是从 X 射线和中子粉末衍射推断出来的。低温磁化率和热容数据显示在 2.3-2.5 K 附近出现异常，与长程磁序相关，这进一步证实了$\mu \mathrm{SR}$和中子衍射数据。在 1.7 K 处收集的中子粉末衍射表明存在由不相称的磁传播矢量k索引的磁布拉格峰 $=(0.148,0.148,0)$ 磁结构最好用纵向自旋密度波来描述，其有序矩位于 $\mathrm{一种}乙$-飞机。基于 CEF 模型的 INS 数据分析表明，在 4.5 meV 和 6.9 meV 附近存在两个磁激发。磁热容量数据表明整体 CEF 分裂为 20.7 meV，然而，在我们的 INS 数据中，20 到 30 meV 之间的激发非常广泛和微弱，但可以提供该能量范围内 CEF 水平的证据，与磁熵。我们基于 CEF-声子模型对 INS 数据的分析表明，4.5 meV 和 6.9 meV 的两个激发起源于 CEF-声子耦合（即，一个 CEF 峰分裂成两个峰，称为振子），总体上分裂 28.16 meV，类似于${\mathrm{铜铝}}_3$ 和 ${\mathrm{陶瓷}}_3$.