Inelastic neutron scattering study of crystalline electric field excitations in a cubic compound PrMgNi4
Inelastic neutron scattering study of crystalline electric field excitations in a cubic compound PrMgNi4
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立方化合物 PrMgNi4 晶体电场激发的非弹性中子散射研究
DOI：
10.1088/1742-6596/2164/1/012052
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
D. T. Adroja
中科院分区：
文献类型：
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作者：
Y. Kusanose;T. Onimaru;Y. Yamane;K. Umeo;T. Takabatake;T. Guidi;D. Le;D. T. Adroja
我们进行了立方MgSnCu 4型结构PrMgNi 4的非弹性中子散射实验。在1.1，2.5，5.9，10.7和11.7毫电子伏的磁激发观察。由于激发的能量对于|Q| < 5 <$− 1，它们被归因于Pr 3+离子的晶体电场（CEF）激发。我们采用CEF参数W=− 3.3 K和x= 0.8的三次Td点群来再现1.1、10.7和11.7 meV的强激发。计算的CEF能级方案揭示了具有四极自由度的Γ 3双重态基态和Γ 4三重态（1.4 meV）、Γ 1单重态（3.4 meV）和Γ 5三重态（13.5 meV）的激发态。然而，这一方案并不能解释在2.5和5.9 meV观测到的两个激发。这些额外的激发可能会产生分裂的双重对称性降低，由于过量的Mg原子占据Pr网站。这种分裂可能是负责的情况下，在PrMgNi 4的长程四极杆顺序。
We performed inelastic neutron scattering experiments on PrMgNi 4 with the cubic MgSnCu 4-type structure. The magnetic excitations were observed at 1.1, 2.5, 5.9, 10.7, and 11.7 meV. Since the energy of the excitations is constant for| Q|< 5 Å− 1, they are ascribed to the crystalline electric field (CEF) excitations of the Pr 3+ ions. We adopted CEF parameters of W=− 3.3 K and x= 0.8 for the cubic T d point group to reproduce the strong excitations at 1.1, 10.7, and 11.7 meV. The calculated CEF level scheme reveals the Γ 3 doublet ground state with the quadrupolar degrees of freedom and the excited states of Γ 4 triplet (1.4 meV), Γ 1 singlet (3.4 meV), and Γ 5 triplet (13.5 meV). This scheme, however, does not explain the observed two excitations at 2.5 and 5.9 meV. These additional excitations may arise from splitting of the doublet by symmetry lowering due to excess Mg atoms occupying the Pr sites. This splitting is probably responsible for the absence of the long-range quadrupole order in PrMgNi 4.