Electron-electron interaction and normal-state transport in superconducting Ti-(Sn,Ge) alloys

We have measured the resistivity as a function of temperature, rho(T), of superconducting Ti-1-x(Sn,Ge)(x) (0.03 less than or similar to x less than or similar to 0.12 for Ti-Sn and 0.03 less than or similar to x less than or similar to 0.07 for Ti-Ge) alloys below 25 K. These alloys are chosen because, upon dilute alloying, their impurity resistivities rho(0) vary readily from approximate to 55 to approximate to 150 mu Omega cm, while their superconducting transition temperatures T-c increase moderately by a factor similar to 60%. We find that the overall behavior of rho(T) can be quantitatively interpreted in terms of the Boltzmann transport AT(n) (with A being a constant and n an exponent) plus a temperature-dependent contribution Delta rho(I) arising from electron-electron interaction effects in the presence of disorder. Particularly, we observe a disorder dependence of Delta rho(I) similar to rho(0)(5/2). We also observe that the screened Coulomb interaction parameter (F) over tilde, defined in the electron-electron interaction theory, becomes much more negative in samples with increasing T-c.