Effect of thermal annealing on electron dephasing in metal thick films

We have studied the effect of thermal annealing on electron dephasing times τ_φ in three-dimensional polycrystalline metals. Measurements are performed on as-sputtered and annealed AuPd and Sb thick films, using weak-localization method. In all samples, we find that τ_φ possesses an extremely weak temperature dependence as T arrow 0. Our results show that the effect of annealing is non-universal, and it depends strongly on the amount of disorder quenched in the microstructures during deposition. The observed ``saturation" behavior of τ_φ cannot be easily explained by magnetic scattering. We suggest that the issue of saturation can be better addressed in three-dimensional, rather than lower-dimensional, structures. This is because of the increased contrast between the ``saturation" and the strong temperature dependence of the electron-phonon scattering in three dimensions.