Magnetotransport properties of ferromagnetic Ga1-xMnxAs layers on a (100)GaAs substrate -: art. no. 063902

The magnetotransport properties of ferromagnetic Ga1-xMnxAs epilayers with Mn mole fractions in the range of x approximate to 2.2%-4.4% were investigated using Hall effect measurements. The temperature-dependent Hall carrier concentration for a metallic sample with x approximate to 2.2% was analyzed assuming an activation energy from two acceptor levels. It was found that the two acceptor levels with activation energies of 129.4 and 31.6 meV at B=0 Oe decreased to 87.6 and 30.7 meV, respectively, at B=5 kOe. The decrease in acceptor activation energy from 129.6 to 87.6 meV was due to the spin splitting of the Mn acceptor level in the ferromagnetic region, and was responsible for the increase in carrier concentration. From magnetic-field-dependent Hall resistance data, the Curie temperature was estimated to be T-C=60 and 70 K for Ga1-xMnxAs samples with x approximate to 2.2 and x approximate to 4.4%, respectively. The magnetoresistance measurements confirmed that the anomalous Hall effect existed in these samples that showed metallic and insulating behavior, respectively. (C) 2005 American Institute of Physics.