A Collective Heavy Fermion State and Superconductivity in Pr$_{1-x}$La$_x$Os$_4$Sb$_{12}$: Specific Heat and Susceptibility Study

C. R. Rotundu; P. Kumar; B. Andraka

paper

A Collective Heavy Fermion State and Superconductivity in Pr $_{1 - x}$ La $_{x}$ Os $_{4}$ Sb $_{12}$ : Specific Heat and Susceptibility Study

arXiv:cond-mat/0402599

Abstract

Low temperature susceptibility and specific heat for single crystals of Pr $_{1 - x}$ La $_{x}$ Os $_{4}$ Sb $_{12}$ (0 $\leq x$ $\leq 1$ ) are reported. La-doping leaves CEF energies of Pr essentially unchanged. The average $T_{c}$ is only weakly affected by the La-substitution and varies approximately linearly between the end-compounds. The second superconducting transition disappears between $x$ =0.05 and 0.1. The discontinuity in $C / T$ at $T_{c}$ , on the other hand, is drastically reduced from about 1000 mJ/K $^{2}$ mol for $x$ =0 to 200 mJ/K $^{2}$ mol for $x$ =0.2. $Δ C / T_{c}$ decreases further for alloys corresponding to $x \geq 0.6$ to the value of a conventional superconductor LaOs $_{4}$ Sb $_{12}$ . This behavior implies non-single impurity origin of the heavy fermion state in PrOs $_{4}$ Sb $_{12}$ . We argue that critical quadrupolar fluctuations are responsible for this heavy fermion state.

A Collective Heavy Fermion State and Superconductivity in Pr1−x​Lax​Os4​Sb12​: Specific Heat and Susceptibility Study

Abstract

A Collective Heavy Fermion State and Superconductivity in Pr $_{1 - x}$ La $_{x}$ Os $_{4}$ Sb $_{12}$ : Specific Heat and Susceptibility Study