Longitudinal Magnetoresistance inn-Type Germanium: Experimental

Measurements of the longitudinal magnetoresistance of single crystals of pure and doped $n$-type germamanium oriented in the $〈100〉$, $〈110〉$, and $〈111〉$ directions have been made in magnetic fields up to 300 kgauss over the temperature interval 20°-300°K. The magnetoresistance ratio $\frac{\rho \mathrm{}\left(H\right)\mathrm{}}{\rho \mathrm{}\left(0\right)\mathrm{}}$ was found to vary linearly with magnetic field strength in the quantum limit. Magnetoresistance ratios less than one were observed and explained on the basis of the many-valley structure of the conduction band. The saturation of magnetoresistance predicted by classical transport theory was observed at the higher end of the temperature range and used to demonstrate a temperature variation of the anisotropy parameter $K$.