发表机构
Tata Institute of Fundamental Research; UGC DAE Consortium for Scientific Research Mumbai Centre（塔塔基础研究所; UGC-DAE科学研究中心孟买中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文通过磁化率、电阻率和比热测量，研究了CeRu$_2$Ge$_2$单晶的铁磁转变（$T_{\ m C}=7.5$K）及各向异性，利用晶场模型定量解释了其磁性质，并证实磁化易轴沿[001]方向与CEF基态一致。
AI 中文摘要
我们报道了对CeRu$_2$Ge$_2$单晶磁性和输运性质的详细各向异性研究。在磁化率、电阻率和比热测量中，观察到在$T_{\ m C} = 7.5$~K处出现清晰的铁磁转变。在磁有序态内的低温下，磁电阻（MR）为正。我们确认了在电阻率、MR和低温比热数据中存在磁振子激发能隙。沿[100]和[001]方向观察到的磁化率和磁化强度的显著各向异性，在晶场（CEF）框架内使用点电荷模型得到了定量解释。分析揭示了包含三个二重态的CEF能级方案，基态和两个激发态分别位于491和671~K，这进一步从比热数据中磁部分的肖特基效应得到证实。与大多数Ce化合物近藤晶格铁磁体（其磁易轴偏离预期的CEF基态）不同，CeRu$_2$Ge$_2$的磁化强度与CEF导出的基态波函数完全一致，磁化易轴沿[001]方向排列。
英文摘要
We report a detailed anisotropic studies on the magnetic and transport properties of a CeRu$_2$Ge$_2$ single crystal. A clear ferromagnetic transition is observed at $T_{\rm C} = 7.5$~K in the magnetic susceptibility, electrical resistivity and heat capacity measurements. The magnetoresistance (MR) is positive at low temperature within the magnetically ordered state. We confirmed the presence of a magnon excitation gap in the resistivity, MR and the low temperature heat capacity data. The pronounced anisotropy observed in the magnetic susceptibility and magnetization along the [100] and [001] directions is quantitatively explained within the crystal electric field (CEF) framework using the point-charge model. The analysis reveals a CEF level scheme comprising three doublets, with a ground state and two excited states at 491 and 671~K, that was further confirmed from the Schottky effect in the magnetic part of the heat capacity data. Unlike most Kondo lattice ferromagnets of Ce compounds, where the magnetic easy axis deviates from the expected CEF ground state, CeRu$_2$Ge$_2$ exhibits magnetization, which is fully consistent with the CEF derived ground state wave function, with the easy axis of magnetization aligned along the [001] direction.
Comments5 figures,10 pages
