Multiband order parameters for the PrOs4Sb12 and PrRu4Sb12 skutterudite superconductors from thermal conductivity...

Thermal conductivity measurements were performed on single crystal samples of the superconducting filled-skutterudite compounds PrOs4Sb12 and PrRu4Sb12 both as a function of temperature and transverse magnetic field. In a zero magnetic field, the low temperature electronic thermal conductivity of PrRu4Sb12 is consistent with a fully gapped Fermi surface. For PrOs4Sb12, residual electronic conduction in the zero-temperature limit is consistent with the presence of nodes in the superconducting energy gap. The electronic thermal conductivity for both compounds shows a rapid rise at low magnetic fields. In PrRu4Sb12, this is interpreted in terms of multiband effects. In PrOs4Sb12, we consider the Doppler shift of nodal quasiparticles and multiband effects.