Anomalous frequency and intensity scaling of collective and local modes in a coupled-spin tetrahedral system Cu2Te2O5Cl2
Anomalous frequency and intensity scaling of collective and local modes in a coupled-spin tetrahedral system Cu2Te2O5Cl2
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耦合自旋四面体系统 Cu2Te2O5Cl2 中集体和局部模式的反常频率和强度缩放
DOI：
10.1103/physrevb.79.024416
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发表时间：
2009
影响因子：
3.7
通讯作者：
P. Lemmens
中科院分区：
文献类型：
--
作者：
K. Y. Choi;H. Nojiri;N. S. Dalal;H. Berger;W. Brenig;P. Lemmens
我们用单晶的拉曼散射研究了耦合自旋四面体系统的磁激发光谱。从热力学数据到有序状态的转变导致了不同的低能磁激发的演化，这些激发叠加了一个宽的极大值。这些模式归因于具有不同局域化程度的磁子和两个磁振子连续体。与其他Néel有序体系的有序参数类似，其中两个模式随着温度的降低而发生显著的能量移动。另外两个模仅表现出可忽略的温度依赖性，并且在有限能量下以连续激发的形式溶解在有序温度以上。这些观测指出了磁性四面体间自由度和四面体内自由度之间的微妙相互作用，这是接近量子临界的系统所预期的。
We report on the magnetic excitation spectrum of the coupled-spin tetrahedral systemusing Raman scattering on single crystals. The transition to an ordered state atevidenced from thermodynamic data leads to the evolution of distinct low-energy magnetic excitations superimposed by a broad maximum. These modes are ascribed to magnons with different degree of localization and a two-magnon continuum. Two of the modes develop a substantial energy shift with decreasing temperature similar to the order parameter of other Néel ordered systems. The other two modes show only a negligible temperature dependence and dissolve above the ordering temperature in a continuum of excitations at finite energies. These observations point to a delicate interplay of magnetic intertetrahedra and intratetrahedra degrees of freedoms as expected for a system in the proximity to quantum criticality.