Crystal field effect on X-ray magnetic circular dichroism spectra at the L2,3 absorption edges of mixed-valence Ce and Yb compounds in high magnetic fields
Crystal field effect on X-ray magnetic circular dichroism spectra at the L2,3 absorption edges of mixed-valence Ce and Yb compounds in high magnetic fields
复制标题
高磁场下Ce、Yb混价化合物L2,3吸收边X射线磁圆二色光谱的晶场效应
DOI：
10.1140/epjb/e2011-11004-8
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
A. Kotani
中科院分区：
文献类型：
--
作者：
A. Kotani
摘要
采用扩展的单杂质Anderson模型，研究了强磁场中晶场对Ce、Yb混价化合物L2、3边X-射线磁性圆二色谱(XMCD)的影响。假定作用在4f电子上的晶场具有立方对称性。
由于晶场、混合价和外加磁场的相互竞争，XMCD谱随磁场的变化呈现出多种特征，如Ce化合物的L2和L3 XMCD强度的分支比R(L2/L3)分别为R(L2/L3)>；1.0和<；1.0，Yb化合物的分支比R(L2/L3)>；0和<；0。
结果表明，XMCD总强度I(L2+L3)随磁场的变化与磁化曲线成正比，而R(L2/L3)能更准确地反映磁场中的基态波函数。提出了一种新的关联XMCD谱、4f磁化强度和基态波函数的方法，并用它讨论了I(L2+L3)与磁化曲线、R(L2/L3)与基态波函数的关系。
Abstract
A theoretical study is presented, with an extended single impurity Anderson model, for the crystal field effect on the X-ray magnetic circular dichroism (XMCD) spectra at L2,3 edges of mixed-valence Ce and Yb compounds in high magnetic fields. The crystal field acting on the 4f electrons is assumed to have cubic symmetry.
Due to the competition among the effects of crystal field, mixed valency, and external magnetic field, the magnetic-field-dependence of XMCD spectra exhibits a variety of features; for instance, the branching ratio, R(L2/L3), of L2 and L3 XMCD intensities of Ce compounds can take R(L2/L3) > 1.0 and <1.0, and that of Yb compounds can take R(L2/L3) > 0 and <0.
It is shown that the magnetic-field-dependence of the total XMCD intensity I(L2 + L3) is proportional to the magnetization curve, but that of R(L2/L3) gives more precise information on the ground state wavefunction in magnetic fields. A new and useful method to correlate the XMCD spectra, the 4f magnetization and the ground state wavefunction is proposed and used to discuss the relation between I(L2 + L3) and the magnetization curve and that between R(L2/L3) and the ground state wavefunction.