The anisotropy parameter alpha ( identical to rho /sub //// rho perpendicular to ) in phonon scattering resistivity of normal hexagonal metals at low temperature is estimated numerically from a very simple formula. There are three different sizes of distortion for the Fermi sphere of a hexagonal metal corresponding to the three different kinds of reciprocal lattice vector. The umklapp scattering process with reciprocal lattice vector corresponding to distortion of the largest gap will be frozen out first as temperature decreases. As a result of this, the anisotropy parameters alpha for all three metals Zn, Cd and Mg irrespective of whether their alpha is greater or less than unity, are found to have peaks in the low-temperature region, in qualitative agreement with experiment.
Journal of Physics F: Metal Physics 8(5), pp.859-863