Superconducting and normal state properties of the heavy fermion compound PrOs4Sb12

The filled skutterudite compound PrOs4Sb12 displays superconductivity with a critical temperature T-c approximate to 1.85K which appears to involve heavy fermion quasiparticles with an effective mass m* similar to 50 - 100 m(e), as inferred from the slope of the upper critical field curve near T, and the specific heat. New measurements of electrical resistivity rho(T) in applied magnetic fields, thermoelectric power, and X-ray diffraction are presented. A peak appears in the drho/dT data for magnetic fields above 4 T that suggests the occurrence of a phase transition in the normal state of PrOs4Sb12 below - 1K.