SUPPRESSION OF SUPERCONDUCTIVITY IN UPT3 SINGLE-CRYSTALS

High-quality single crystals of UPt3 have been prepared by vertical fl oat-zone refining in ultrahigh vacuum. We find that the superconductin g transition temperature can be varied systematically by annealing, re vealing that the transition temperature intrinsic to UPt3 is 563+/-5 m K. The suppression of I:he superconducting transition from defects is consistent with a modified Abrikosov Gor'kov formula that includes ani sotropic pairing, Fermi-surface anisotropy, and anisotropic scattering by defects. [SC163-1829(98)50426-2].