发表机构
ISIS Neutron and Muon Source, STFC, Rutherford Appleton Laboratory; Jawaharlal Nehru Centre for Advanced Scientific Research; Department of Physics, Indian Institute of Technology (BHU) Varanasi; Highly Correlated Matter Research Group, Physics Department, University of Johannesburg; Institut Laue-Langevin; Scientific Computing Department, STFC, Rutherford Appleton Laboratory; Scientific Computing Department, STFC Daresbury Laboratory; MPA-Q, Los Alamos National Laboratory（英国科学和技术设施委员会拉瑟福德阿普尔顿实验室中子与μ子源; 贾瓦哈拉尔·尼赫鲁高级科学研究中心; 印度技术学院瓦拉纳西物理系; 约翰内斯堡大学高度相关物质研究组; 朗之万研究所; 英国科学和技术设施委员会拉瑟福德阿普尔顿实验室科学计算部; 英国科学和技术设施委员会达尔斯伯里实验室科学计算部; 洛斯阿拉莫斯国家实验室）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
通过μSR、中子衍射和非弹性散射实验，发现Ce₂Te₅在5K以下形成单一铁磁有序相，但仅一个Ce位点携带磁矩，低温异常源于竞争相互作用与晶场效应。
AI 中文摘要
Ce$_2$Te$_5$是一种层状$f$电子范德瓦尔斯磁体，其中降低的维度和不等价的Ce位点导致竞争性磁相互作用。我们利用μ子自旋弛豫（$\mu$SR）、中子粉末衍射（NPD）和非弹性中子散射（INS）研究了其磁性基态。零场$\mu$SR揭示在$T_{\mathrm{C}} = 5.0(1)$~K以下静态磁性开始出现，随后在$T_{\mathrm{2}} = 2.3(2)$~K处内部场出现额外异常，与块体热力学和输运测量中观察到的特征一致。相比之下，在$0.05-8$~K范围内收集的NPD数据显示，在$T_{\mathrm C}$以下存在单一长程有序磁相，磁布拉格强度在$T_{\mathrm C}$处消失，且没有证据表明在降至基态温度过程中存在额外的结构或磁相变。有序态的特征是公度传播矢量$\mathbf{k}=(0,0,0)$以及Ce磁矩沿晶格$b$轴铁磁排列。值得注意的是，两个晶体学上不同的Ce位点中仅有一个在0.05~K时携带约$0.85(3)~\mu_{\mathrm B}$每Ce的有序磁矩。INS测量确定了Ce$^{3+}$的晶体电场（CEF）能标，揭示出位于7.94和21.46~meV的低能激发以及具有强单离子各向异性的Kramers双重态基态。这些结果表明，Ce$_2$Te$_5$经历单一对称性破缺的磁相变，而额外的低温异常反映了由竞争相互作用和CEF效应驱动的有序态的微妙修正。
英文摘要
Ce$_2$Te$_5$ is a layered $f$-electron van der Waals magnet in which reduced dimensionality and inequivalent Ce sites give rise to competing magnetic interactions. We investigate its magnetic ground state using muon spin relaxation ($μ$SR), neutron powder diffraction (NPD), and inelastic neutron scattering (INS). Zero-field $μ$SR reveals an onset of static magnetism below $T_{\mathrm{C}} = 5.0(1)$~K, followed by an additional anomaly in the internal field at $T_{\mathrm{2}} = 2.3(2)$~K, consistent with features observed in bulk thermodynamic and transport measurements. In contrast, NPD data collected between $0.05-8$~K reveal a single long-range ordered magnetic phase below $T_{\mathrm C}$, with the magnetic Bragg intensities vanishing at $T_{\mathrm C}$ with no evidence for additional structural or magnetic phase transitions down to base temperature. The ordered state is characterized by a commensurate propagation vector $\mathbf{k}=(0,0,0)$ and ferromagnetic alignment of Ce moments along the crystallographic $b$ axis. Remarkably, only one of the two crystallographically distinct Ce sites carries an ordered moment of $\sim 0.85(3)~μ_{\mathrm B}$ per Ce at 0.05~K. INS measurements establish the crystal electric field (CEF) energy scale of Ce$^{3+}$, revealing low-lying excitations at 7.94 and 21.46~meV and a Kramers doublet ground state with strong single-ion anisotropy. These results demonstrate that Ce$_2$Te$_5$ undergoes a single symmetry-breaking magnetic transition, while additional low-temperature anomalies reflect subtle modifications of the ordered state driven by competing interactions and CEF effects.
Comments14 pages, 9 figures
