Magnetoresistance of GaP04 As06 whiskers at low temperatures

The magnetic resistance and electrical conductivity of the GaP ₀₄ As ₀₆ whiskers doped with silicon with a concentration of acceptor impurity (N _a = (1×10 ¹⁷ ÷5×10 ¹⁸ cm ^-3 ) and P content (x=40 at. %) were investigated. The magnetoresistance of the GaP ₀₄ As ₀₆ with the concentration of charge carriers in the vicinity to the metal-insulator transition at the temperature of liquid helium is described by a quadratic dependence on the magnetic field and is mainly determined by the conductivity of the localized states A+ of the upper Hubbard zone. The negative magneoresistance is found, and its magnitude reaches 7 % at a magnetic field induction of 4.5 T and a temperature of 4.2 K, which is probably due to the formation of the hole pairs connected with antiferromagnetic exchange interaction of the magnetic moments in the process of hopping conduction on the delocalized states of the upper Hubbard zone.