Probing the superconductivity ofPrPt4Ge12through Ce substitution

Abstract

We report measurements of electrical resistivity, magnetic susceptibility, specific heat, and thermoelectric power on the system Pr${}_{1\ensuremath{-}x}$Ce${}_{x}$Pt${}_{4}$Ge${}_{12}$. Superconductivity is suppressed with increasing Ce concentration up to $x=0.5$, above which there is no evidence for superconductivity down to 1.1 K. The Sommerfeld coefficient $\ensuremath{\gamma}$ increases with increasing $x$ from $\ensuremath{\sim}$48 mJ/mol K${}^{2}$ up to $\ensuremath{\sim}$120 mJ/mol K${}^{2}$ at $x=$ 0.5, indicating an increase in strength of electronic correlations. The temperature dependence of the specific heat at low temperatures evolves from roughly ${T}^{3}$ for $x=$ 0 to e${}^{\ensuremath{-}\ensuremath{\Delta}/T}$ behavior for $x=$ 0.05 and above, suggesting a crossover from a nodal to a nodeless superconducting energy gap or a transition from multiband to single-band superconductivity. Fermi-liquid behavior is observed throughout the series in low-temperature magnetization, specific heat, and electrical resistivity measurements.