Anomalous temperature and disorder dependence of the electron–phonon scattering time in impure metals

We have measured the electron–phonon scattering time, τep, in disordered metals at liquid-helium temperatures, using weak-localization method. The temperature and disorder dependence of τep is determined for AgPd and AuPd thick films, and V100−xAlx alloys. In all three cases, we find an anomalous temperature and disorder dependence of τep−1∝T2ℓ, where ℓ is the electron elastic mean free path. This temperature and disorder behavior cannot be explained in terms of current theoretical concepts for the electron–phonon interaction in impure conductors. Current theory predicts a form of either τep−1∝T4ℓ or τep−1∝T2ℓ−1 in the dirty limit, depending on the nature of the defects.