  We have studied the magnetic-field and concentration dependences of the
magnetizations of the hole and Mn subsystems in diluted ferromagnetic
semiconductor Ga_{1-x}Mn_xAs. 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 Tc 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 Tc(x) and p(x) on different Ga_{1-x}Mn_xAs samples and
stress the need of further detailed experimental work to assure that the
experimental measurements are reproducible.
