Umklapp Processes and the Low-Temperature (T<7°K) Electrical Resistivity of Aluminum

Abstract
Recently, a sharp steplike temperature dependence in the electrical resistivity of aluminum in the vicinity of 4°K has been observed and ascribed to the exponential onset of electron-phonon umklapp scattering. There are, however, theoretical arguments that umklapp processes in aluminum in this temperature region do not account for a sharp temperature dependence of the kind observed. Accurate resistivity measurements (0.02% relative accuracy) are presented in support of these arguments.