Crystalline electric field excitations in the quantum spin liquid candidate NaYbSe2
Crystalline electric field excitations in the quantum spin liquid candidate NaYbSe2
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量子自旋液体候选物 NaYbSe2 中的晶体电场激发
DOI：
10.1103/physrevb.103.035144
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发表时间：
2021-01-27
影响因子：
3.7
通讯作者：
Zhang, Qingming
中科院分区：
文献类型：
--
作者：
Zhang, Zheng;Ma, Xiaoli;Zhang, Qingming
采用非弹性中子散射（INS）和拉曼散射（RS）实验，我们全面研究了NaYbSe 2中的晶体电场（CEF）激发，NaYbSe 2是一种新的量子自旋液体候选者，属于一个大家族的三角晶格稀土硫族化合物，具有高对称性结构和可忽略的结构、自旋和电荷无序效应.我们可以在5 K下识别15.8，24.3和30.5 meV的CEF激发。INS光谱的所选切割被很好地再现，具有g（ab）= 2.9和g（c）= 1的大的各向异性。基于点电荷模型的计算进一步证实了CEF激发。有趣的是，NaYbSe 2表现出不寻常的偏移CEF水平更高的能量随着温度的升高。此外，接近第一CEF激发的拉曼模式显示出随着温度降低的极大软化。这些异常的情况下，在nanostructural材料NaLuSe 2允许我们认为，NaYbSe 2采用了异常强大的CEF-声子共振耦合没有报告中的任何三角晶格稀土硫属化物。CEF激发的确定表明在低温下有效自旋1/2的图像的有效性。
By employing inelastic neutron scattering (INS) and Raman scattering (RS) experiments, we comprehensively investigate crystalline electric field (CEF) excitations in NaYbSe2, a new quantum spin liquid candidate that belongs to a large family of triangular-lattice rare-earth chalcogenides with a high-symmetry structure and negligible structural, spin, and charge disordering effects. We can identify CEF excitations at 15.8, 24.3, and 30.5 meV at 5 K. The selected cuts of the INS spectra are well reproduced with a large anisotropy of g(ab) = 2.9 and g(c) = 1. The CEF excitations are further confirmed by our calculations based on the point charge model. Interestingly, NaYbSe2 exhibits an unusual shift of CEF levels to higher energies with increasing temperatures. Further, the Raman mode close to the first CEF excitation shows an anomalously large softening with decreasing temperatures. The absence of these anomalies in the nonmagnetic isostructural material NaLuSe2 allows us to argue that NaYbSe2 incorporates an unusually strong CEF-phonon resonancelike coupling not reported in any of the triangular-lattice rare-earth chalcogenides. The determination of the CEF excitations suggests the validity of the picture of an effective spin 1/2 at low temperatures.