Magnetic-field effects in defect-controlled ferromagnetic Ga1-xMnxAs semiconductors

We have studied the magnetic-field and concentration dependences of the magnetizations of the hole and Mn subsystems in diluted ferromagnetic semiconductor Ga1-xMnxAs. A mean-field approximation to the hole-mediated interaction is used, in which the hole concentration p(x) is parametrized in terms of a fitting (of the hole effective mass and hole/local moment coupling) to experimental data on the T-c critical temperature. The dependence of the magnetizations with x, for a given temperature, presents a sharply peaked structure; with maxima increasing with applied magnetic field, which indicates that application to diluted-magnetic-semiconductor devices would require quality control of the Mn-doping composition. We also compare various experimental data for T-c(x) and p(x) on different Ga1-xMnxAs samples and stress the need of further detailed, experimental work to assure that the experimental measurements are reproducible. (C) 2003 American Institute of Physics. [DOI: 10.1063/1.1534622].