Ferromagnetic ordering along the hard axis in the Kondo lattice YbIr3Ge7
Ferromagnetic ordering along the hard axis in the Kondo lattice YbIr3Ge7
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DOI：
10.1103/physrevb.99.121109
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发表时间：
2019-01
影响因子：
3.7
通讯作者：
B. Rai;M. Stavinoha;J. Banda;D. Hafner;Katherine A. Benavides;D. Sokolov;J. Chan;M. Brando;Chien-Lung Huang;E. Morosan
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文献类型：
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作者：
B. Rai;M. Stavinoha;J. Banda;D. Hafner;Katherine A. Benavides;D. Sokolov;J. Chan;M. Brando;Chien-Lung Huang;E. Morosan
铁磁性近藤晶格化合物远不如它们的反铁磁类似物常见。在这项工作中，我们发现了一种新的铁磁性近藤晶格化合物YbIr3Ge7。像几乎所有铁磁性近藤晶格系统一样，YbIr3Ge7显示出与晶体电场(CEF)易轴垂直的磁矩排列。YbIr3Ge7的独特之处在于它是这类化合物中唯一具有三角磁位点对称性的菱面体结构的成员，并且它在局部磁矩位置缺乏破缺的反转对称性。交流磁化率、磁化强度和比热测量表明，YbIr3Ge7的Kondo温度TK=14K，居里温度TC=2.4K，尽管基态Kramers双重态具有很大的CEF各向异性，但沿[100]硬质CEF轴存在铁磁有序，[001]方向的饱和磁矩比[100]方向的饱和磁矩大近4倍。这意味着考虑交换相互作用中的各向异性来解释硬轴有序化的机制是不可能的。另一方面，Tc处宽广的二阶相变有利于涨落诱导机制。
Ferromagnetic Kondo lattice compounds are far less common than their antiferromagnetic analogs. In this work, we report the discovery of a new ferromagnetic Kondo lattice compound, YbIr3Ge7. Like almost all ferromagnetic Kondo lattice systems, YbIr3Ge7 shows magnetic order with moments aligned orthogonal to the crystal electric field (CEF) easy axis. YbIr3Ge7 is unique in that it is the only member of this class of compounds that crystallizes in a rhombohedral structure with a trigonal point symmetry of the magnetic site, and it lacks broken inversion symmetry at the local moment site. AC magnetic susceptibility, magnetization, and specific heat measurements show that YbIr3Ge7 has a Kondo temperature TK = 14 K and a Curie temperature TC = 2.4 K. Ferromagnetic order occurs along the crystallographic [100] hard CEF axis despite the large CEF anisotropy of the ground state Kramers doublet with a saturation moment along [001] almost four times larger than the one along [100]. This implies that a mechanism which considers the anisotropy in the exchange interaction to explain the hard axis ordering is unlikely. On the other hand, the broad second-order phase transition at TC favors a fluctuation-induced mechanism.