Superconductivity and crystalline electric field effects in the filled skutterudite series Pr ( Os 1 − x Ru x ) 4 Sb 12
Superconductivity and crystalline electric field effects in the filled skutterudite series Pr ( Os 1 − x Ru x ) 4 Sb 12
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填充方钴矿系列Pr ( Os 1 − x Ru x ) 4 Sb 12 中的超导与晶体电场效应
DOI：
10.1103/physrevb.69.024523
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发表时间：
2003
影响因子：
3.7
通讯作者：
M. Maple
中科院分区：
文献类型：
--
作者：
N. A. Frederick;T. Do;P. Ho;N. Butch;V. Zapf;M. Maple
对填充方钴矿系列Pr（Os 1 -xRux）4Sb 12单晶进行了X射线粉末衍射、磁化率ε（T）和电阻率ρ（T）测量。一端（x=0）伊萨超导临界温度Tc = 1.85K的重费米子超导体，另一端（x= 1）是Tc = 1 K的常规超导体。晶格常数a随着Ru浓度x的增加而近似线性地减小。当Ru（Os）取代Os（Ru）时，Tc随取代基浓度近似线性下降，并在x=0.6时出现最小值Tc = 0.75K，表明两种超导性相互竞争.由于Pr 3 +的九重简并Hund规则J=4多重态的分裂，在晶体c（T）和ρ（T）中观察到晶体电场效应，基态和第一激发态之间的分裂随x的增加而单调增加.对于所有x值，对π d c（T）和ρ（T）数据的拟合与Γ 3双峰基态一致，尽管对于端员化合物（x = 0或x = 1）附近的x值，可以获得对于Γ 1基态的合理拟合。
X-ray powder-diffraction, magnetic-susceptibility Χ (T), and electrical resistivity ρ(T) measurements were made on single crystals of the filled skutterudite series Pr(Os 1 - x Ru x ) 4 Sb 1 2 . One end of the series (x=0) isa heavy fermion superconductor with a superconducting critical temperature T c =1.85 K, while the other end (x= I ) is a conventional superconductor with T c 1 K. The lattice constant a decreases approximately linearly with increasing Ru concentration x. As Ru (Os) is substituted for Os (Ru), T c decreases nearly linearly with substituent concentration and exhibits a minimum with a value of T c = 0.75 K at x=0.6, suggesting that the two types of superconductivity compete with one another. Crystalline electric field effects in Χ d c (T) and ρ(T) due to the splitting of the Pr 3 + ninefold degenerate Hund's rule J=4 multiplet are observed throughout the series, with the splitting between the ground state and the first excited state increasing monotonically as x increases. The fits to the Χ d c (T) and ρ(T) data are consistent with a Γ 3 doublet ground state for all values of x, although reasonable fits can be obtained for a Γ 1 ground state for x values near the end member compounds (x = 0 or x = 1).