IMPURITY SCATTERING AND TRIPLET SUPERCONDUCTIVITY IN UPT3

Substitution of rare earths (R), Th, and Zr for U in UPt3 depresses the superconducting transition temperature T-c at an initial rate (Delta T-c/x), where x is the impurity concentration, that increases linearly with increasing residual resistivity rho(0), indicating that the primary pair breaking mechanism is impurity potential scattering. The scaling of (Delta T-c/x) with rho(0) is strong evidence for anisotropic superconductivity in UPt3. The absence of a correlation of (Delta T-c/x) with the de Gennes factor of the R ions suggests that the superconducting order parameter in the A phase of UPt3 has odd parity.