Superconducting and normal state properties of the systems La1-xMxPt4Ge12 (M = Ce, Th)
White, Bryan D.
Breindel, Alexander J.
Maple, M. Brian
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CitationHuang, K., Yazici, D., White, B. D., Jeon, I., Breindel, A. J., Pouse, N., & Maple, M. B. (2016). Superconducting and normal state properties of the systems La 1− x M x Pt 4 Ge 12 (M= Ce, Th). Physical Review B, 94(9), 094501.
Electrical resistivity, magnetization, and specific heat measurements were performed on polycrystalline samples of the filled-skutterudite systems La1−xMxPt4Ge12 (M = Ce, 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 power-law to exponential behavior, which may be an indication for multi-band 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.