Anomalous Enhancement of Seebeck Coefficient in Pr-Based 1-2-20 System with Non-Kramers Doublet Ground States
Anomalous Enhancement of Seebeck Coefficient in Pr-Based 1-2-20 System with Non-Kramers Doublet Ground States
复制标题
基于 Pr 的非 Kramer 双态基态 1-2-20 系统中塞贝克系数的反常增强
DOI：
10.1088/1742-6596/592/1/012025
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
T. Takabatake
中科院分区：
文献类型：
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作者：
Y. Machida;T. Yoshida;T. Ikeura;K. Izawa;A. Nakama;R. Higashinaka;Y. Aoki;H. Sato;A. Sakai;S. Nakatsuji;N. Nagasawa;K. Matsumoto;T. Onimaru;T. Takabatake
对Pr基1-2-20系统PrTr 2 X 20（Tr= Ti，Ta，V，Ir，X= Al，Zn）的非Kramers双重基态进行了低温Seebeck系数S/T测量.对于PrTr 2X20（X= Al），我们发现其S/T很大，相当于重费米子金属的S/T.相比之下，PrIr 2 Zn 20的S/T相当小，与普通金属的S/T在同一个数量级，尽管在整个系统中索末菲系数γ普遍增强。S/T与γ之间的准普适关系以及Kadowaki-Woods关系表明，PrTr 2Al 20中的质量增强是由于f电子与导电电子的杂化所致.我们还发现PrIr 2 Zn 20的小S/T在四极有序相附近的电场下在低温下得到增强，并且在相同的区域内，电阻率遵循二次温度依赖关系，具有很陡的斜率，这是费米液体的特征。结果表明，出现了一个非平凡的相干态与相当大的质量增强与四极自由度。
Low-temperature Seebeck coefficient S/T measurements have been performed on Pr-based 1-2-20 system, PrTr 2 X 20 (Tr= Ti, Ta, V, Ir, X= Al, Zn) with non-Kramers doublet ground states. For PrTr 2 X 20 with X= Al, we find a large S/T, which amounts to those of heavy fermion metals. By contrast, S/T for PrIr 2 Zn 20 is found to be considerably small as the same order of magnitude as those of ordinary metals, despite the commonly enhanced Sommerfeld coefficient γ throughout the system. A satisfactory of the quasi-universal relation between S/T and γ as well as the Kadowaki-Woods relation demonstrates that the mass enhancement is realized in PrTr 2 Al 20 due to the hybridization between f-electrons and the conduction electrons. We also find that the small S/T of PrIr 2 Zn 20 is enhanced at low temperatures under the fields on the verge of quadrupole ordered phase, and in the same regime, the electrical resistivity follows the quadratic temperature dependence with a steep slope as a characteristic of Fermi liquid. The results imply an emergence of a nontrivial coherent state with sizable mass enhancement associated with the quadrupole degree of freedom.