A model for the anomalous magnetoresistance in amorphous semiconductors

Abstract

A semiclassical random walk hopping model is proposed in order to explain the anomalous magnetoresistance in amorphous germanium and silicon in the hopping regime. A general expression is derived for the magnetoresistance. The magnetoresistance is deduced to be the result of the modification of the spin-flip relaxation time by the external magnetic field. Explicit formulae are derived within the variable range hopping theory of Mott and the spin relaxation model described previously by the present authors. The model can then account for the variety of experimental observations in these materials.