Giant Negative Magnetoresistance of (Ga,Mn)As/GaAs in the Vicinity of a Metal–Insulator Transition

We have studied the transport and magnetic properties of Ga1—xMnxAs/GaAs with different Mn content (0.015 < x < 0.071). In these magnetic semiconductors, the exchange interaction between the carriers and the localized magnetic moments leads to unique transport properties. In this paper, we discuss an insulator–metal–insulator transition and a giant negative magnetoresistance observed in the vicinity of the metal–insulator transitions.