Suppression of Superconductivity in UPt_3 Single Crystals
  High quality single crystals of UPt_3 have been prepared by vertical float-zone refining in ultra-high vacuum. We find that the superconducting transition temperature can be varied systematically by annealing, revealing that the transition temperature intrinsic to UPt_3 is 563 +/- 5 mK. The suppression of the superconducting transition from defects is consistent with a modified Abrikosov-Gor'kov formula that includes anisotropic pairing, Fermi surface anisotropy, and anisotropic scattering by defects. 
J.B. Kycia, J.I. Hong, M.J. Graf, J.A. Sauls, D.N. Seidman, W.P.   Halperin (Northwestern University)