Analysis of magnetic field dependent mobility in ferromagnetic Ga1−xMnxAs layers

The magneto-transport properties of ferromagnetic Ga1−xMnxAs epilayers with Mn mole fractions in the range of x≈2.2–4.4% were investigated through Hall effect measurements. The magnetic field-dependent Hall mobility for a metallic sample with x≈2.2% in the temperature range of T=0–300 K was analyzed by magnetic field-dependent mobility model including an activation energy of Mn acceptor level. This model provides outstanding fits to the measured data up to T=300 K. It was found that the acceptor levels with activation energies of 112 meV at B=0 Oe decreased to 99 meV at B=5 kOe in the ferromagnetic region. The decrease in acceptor activation energy was due to the spin splitting of the Mn acceptor level in the ferromagnetic region, and was responsible for increase in carrier concentration.