Magnetoresistance of Holes in Germanium and Silicon with Warped Energy Surfaces

The series-expansion method which has been described in an earlier paper has been used to obtain expressions for the magnetoconductivity coefficients in the case of warped energy surfaces and low magnetic fields. Using the experimental values of Hall coefficient and conductivity, and assuming a relaxation time of the form τ=lε^-λ, where l is a temperature-dependent coefficient, ε is the energy of the carriers, and λ is a parameter which most suitably represents the scattering processes, we have calculated the magneto-resistance coefficients in p-type germanium and silicon. The results of these calculations are used to interpret the experimentally derived directional magnetoresistance effects and also the variation of magnetoresistance with magnetic field in these materials.