Superconductivity in the correlated pyrochlore Cd2Re2O7 -: art. no. 180503

We report the observation of superconductivity in high-quality Cd2Re2O7 single crystals with room-temperature pyrochlore structure. Resistivity and ac susceptibility measurements establish an onset transition temperature T-c(onset) = 1.47 K with transition width DeltaT(c) = 0.25 K. In applied magnetic field. the resistive transition shows a type-II character. with an approximately linear temperature-dependence of the upper critical field H-c2. The bulk nature of the superconductivity is confirmed by the specific heat jump with DeltaC =3 7.9 mJ/mol-K. Using the gamma value extracted from normal-state specific heat data. we obtain DeltaC/gammaT(c), = 1.29. close to the weak coupling BCS value. In the normal state, a negative Hall coefficient below 100 K suggests electronlike conduction in this material. The resistivity exhibits a quadratic T dependence between 2 and 60 K. i.e., rho = rho (0) + AT(2), indicative of Fermi-liquid behavior. The values of the Kadowaki-Woods ratio A/gamma (2) and the Wilson ratio are comparable to that for strongly correlated materials.