Change in the magnetoresistance of n-GaAs in an electric field

The effect of an electric field on the magnitude of the magnetoresistance in epitaxial n-GaAs films with free carrier concentrations n_e=4.0.10¹⁵–1.12. 10¹⁶ cm^–3 at T=4.2K was investigated. It was found that in weak electric and magnetic fields for E < E_b (E_b is the intensity of the low-temperature impurity breakdown field) the magnetoresistance (MR) is negative, and for EE_b only a positive magnetoresistance is observed. The experimental results are explained by a change in the concentration of centers with a magnetic moment and of electrons in the impurity band in prebreakdown electric fields.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 51–55, July, 1981.