Low-T magnetotransport data on epitaxial n-type GaAs, in the variable-range hopping regime, are presented with emphasis on negative-magnetoresistance effects at low magnetic fields. A minimum in the variation of the magnetoresistance as a function of the magnetic field is observed. The negative part of the magnetoresistance is in good agreement with a model which accounts for the Zeeman splitting of the localized energy levels. A weak dependence of the characteristic temperature of Mott’s law on the magnetic field is observed.

• Received 22 January 1988

DOI:https://doi.org/10.1103/PhysRevB.38.10933