Superconducting Characteristics of Filled Skutterudites LaPt4Ge12 and PrPt4Ge12: 73Ge-NQR/NMR Studies
Superconducting Characteristics of Filled Skutterudites LaPt4Ge12 and PrPt4Ge12: 73Ge-NQR/NMR Studies
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DOI：
10.1143/jpsj.79.063702
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发表时间：
2010-06-01
影响因子：
1.7
通讯作者：
Haller, Eugene E.
中科院分区：
文献类型：
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作者：
Kanetake, Fumiya;Mukuda, Hidekazu;Haller, Eugene E.
用Ge-73核四极共振(NQR)研究了填充型Skutterudite LaPt4Ge12(T_c=8：3K)和PrPt4Ge12(T-c=7.9K)的零场超导特性。在PrPt4Ge12中，核自旋-晶格驰豫速率(73)(1/T-1)在T-c以下有一个相干峰，表明PrPt4Ge12的超导电性是用传统的BCS机制来解释的。结果不仅用各向同性的S波隙模型重现，而且用各向异性的点节点S波隙模型重现。在常规超导体LaPt4Ge12中，由于准粒子的某些衰减效应，(73)(1/T-1)中的相干峰被显著抑制。我们注意到，LaPt4Ge12和PrPt4Ge12的T(C)S高于其他RPt4Ge12的原因可能是由于较大的态密度，而不是由于R离子可能的摇摆而产生的一些局域非简谐声子模。
We report on the superconducting characteristics of the filled skutterudites LaPt4Ge12 (Tc = 8: 3 K) and PrPt4Ge12 (T-c 7.9 K) by Ge-73-nuclear quadrupole resonance (NQR) at a zero field. In PrPt4Ge12, the nuclear spin-lattice relaxation rate (73)(1/T-1) has revealed a coherence peak just below T-c, indicating that the superconductivity of PrPt4Ge12 is accounted for in terms of the conventional BCS regime. The result was consistently reproduced by not only an isotropic s-wave gap model but also an anisotropic s-wave gap model with a point node. In the conventional superconductor LaPt4Ge12, the coherence peak in (73)(1/T-1) is markedly suppressed owing to some damping effect of quasiparticles. We note that the T(c)s of LaPt4Ge12 and PrPt4Ge12 being higher than that of other RPt4Ge12 may be attributed to the larger density of states, not to some local anharmonic phonon modes derived from the possible rattling of R ions.