Evolution of superconductivity in Pr$_{1-x}$La$_{x}$Os$_{4}$Sb$_{12}$: Upper critical field measurements

C. R. Rotundu; H. Tsujii; P. Kumar; B. Andraka; H. Sugawara; Y. Aoki; H. Sato

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Evolution of superconductivity in Pr$_{1-x}$La$_{x}$Os$_{4}$Sb$_{12}$: Upper critical field measurements

C. R. Rotundu·H. Tsujii·P. Kumar·B. Andraka·H. Sugawara·Y. Aoki·H. Sato

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Abstract

Measurements of the upper critical field $H_{c2}$ near $T_c$ of Pr$_{1- x}$La$_{x}$Os$_{4}$Sb$_{12}$ were performed by specific heat. A positive curvature in $H_{c2}$ versus $T$ was observed in samples and concentrations exhibiting two superconducting transitions. These results argue against this curvature being due to two-band superconductivity. The critical field slope - $dH_{c2}/dT$ suggests the existence of a crossover concentration $x_{cr} \approx 0.25$, below which there is a rapid suppression of effective electron mass with La-alloying. This crossover concentration was previously detected in the measurement of the discontinuity of $C/T$ at $T_c$.

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C. R. Rotundu, H. Tsujii, P. Kumar, B. Andraka, H. Sugawara, Y. Aoki, H. Sato. 2006-06-28. Evolution of superconductivity in Pr$_{1-x}$La$_{x}$Os$_{4}$Sb$_{12}$: Upper critical field measurements. https://arxiv.org/abs/cond-mat/0606730

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