Evidence for two superconducting gaps in the unconventional superconductor PrPt4Ge12
Evidence for two superconducting gaps in the unconventional superconductor PrPt4Ge12
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DOI：
10.1080/14786435.2012.691218
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发表时间：
2012-01-01
影响因子：
1.6
通讯作者：
Roy, S. B.
中科院分区：
文献类型：
--
作者：
Chandra, L. S. Sharath;Chattopadhyay, M. K.;Roy, S. B.
我们报告了非常规超导体 PrPt4Ge12 在超导状态下的磁化测量结果。在 5.5 K 附近的下临界场 H-C1(T) 和上临界场 H-C2(T) 的温度依赖性中观察到明显的正曲率。发现零场临界电流密度 J(C)(T, H = 0) 随温度几乎呈线性变化。我们认为这些观察到的特征是由于材料中存在两个超导间隙所致。标准化超流体密度是根据 H-C1 的温度依赖性估算的。我们使用两间隙模型对标准化超流体密度进行详细分析，表明较大间隙中存在线节点。 H-C2(T)线可以用Usadel方程拟合，并且H-C2(T)中的正曲率与超导的二能隙图一致。
We report the results of magnetization measurements on the unconventional superconductor PrPt4Ge12 in its superconducting state. A distinct positive curvature is observed in the temperature dependence of the lower critical field H-C1(T) and the upper critical field H-C2(T) around 5.5 K. The zero field critical current density J(C)(T, H = 0) is found to vary nearly linearly with temperature. We argue that these observed features are due to the existence of two superconducting gaps in the material. The normalized superfluid density is estimated from the temperature dependence of H-C1. Our detailed analysis of the normalized superfluid density using a two-gap model indicates the presence of line nodes in the larger gap. The H-C2(T) line can be fitted with the Usadel equations, and the positive curvature in H-C2(T) is shown to be consistent with the two-gap picture of superconductivity.