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Electrical resistivity, magnetization, and specific heat measurements were performed on polycrystalline samples of the filled-skutterudite systems La1−xMxPt4Ge12 (M = Ce and Th). Superconductivity in LaPt4Ge12 was quickly suppressed with Ce substitution and no evidence for superconductivity was found down to 1.1 K for x > 0.2. Temperature-dependent specific heat data at low temperatures for La1−xCexPt4Ge12 show a change from powerlaw to exponential behavior, which may be an indication for multiband superconductivity in LaPt4Ge12. A similar crossover was observed in the Pr1−xCexPt4Ge12 system. However, the suppression rates of the superconducting transition temperatures Tc(x) in the two systems are quite disparate, indicating a difference in the nature of superconductivity, which is conventional in LaPt4Ge12 and unconventional in PrPt4Ge12. In comparison, a nearly linear and smooth evolution of Tc with increasing Th was observed in the La1−xThxPt4Ge12 system, with no change of the superconducting energy gap in the temperature dependence of the specific heat, suggesting similar types of superconductivity in both the LaPt4Ge12 and ThPt4Ge12 compounds.
Huang, K.; Yazici, D.; White, Benjamin D.; Jeon, I.; Breindel, A. J.; Pouse, N.; and Maple, M. B., "Superconducting and normal state properties of the systems La1−xMxPt4Ge12 (M=Ce,Th)" (2016). All Faculty Scholarship for the College of the Sciences. 217.
Physical Review B
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