Change of the effective spin degeneracy in CeNi9−xCuxGe4 due to the interplay between Kondo and crystal field effects
Change of the effective spin degeneracy in CeNi9−xCuxGe4 due to the interplay between Kondo and crystal field effects
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由于近藤效应和晶体场效应之间的相互作用，CeNi9−xCuxGe4 中有效自旋简并度的变化
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
E. Scheidt
中科院分区：
文献类型：
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作者：
L. Peyker;C. Gold;W. Scherer;H. Michor;T. Unruh;G. Simeoni;A. Senyshyn;D. Adroja;O. Stockert;E. Scheidt
对重费米子体系CeNi8.6Cu0.4Ge4和CeNi8CuGe4进行了弹性和非弹性中子散射实验，研究了Ni/Cu取代对晶体场参数的影响，并确定了CeNi9−xCuxGe4中量子临界的驱动力。讨论了竞争RKKY和Kondo相互作用的相关性以及晶体场参数的变化。通过中子粉末衍射研究确定了镍被铜原子取代的晶体位置。此外，准弹性和非弹性中子散射研究提供了有关Ni/Cu取代导致的Kondo性质和晶体场参数变化的详细信息。因此，随着Cu浓度的增加，晶体场基态的有效自旋简并降低被确定为CeNi9−xCuxGe4量子临界性的一个重要控制参数。这些实验的结果与热功率的测量结果相辅相成。
Elastic and inelastic neutron scattering experiments were carried out on the heavy-fermion systems CeNi8.6Cu0.4Ge4 and CeNi8CuGe4 to study i) the influences of Ni/Cu substitution on the crystal field parameters and to identify ii) the driving forces of quantum criticality in CeNi9−xCuxGe4. The relevance of competing RKKY and Kondo interactions and changes of the crystal field parameters is discussed. The crystallographic site where the Ni replacement by copper atoms takes place is identified by neutron powder diffraction studies. Furthermore, quasi-elastic and inelastic neutron scattering studies provide detailed information regarding the Kondo properties and the changes of the crystal field parameters resulting from the Ni/Cu replacement. Hence, a reduction of the effective spin degeneracy of the crystal field ground state with increasing Cu concentration is identified as one important control parameter of quantum criticality in CeNi9−xCuxGe4. The results of these experiments are complemented by measurements of the thermopower.