Manganese concentration and low-temperature annealing dependence ofGa1−xMnxAsby x-ray absorption spectroscopy

The Mn-site-projected electronic structure of the diluted magnetic semiconductors ${\mathrm{Ga}}_{1-x}{\mathrm{Mn}}_x\mathrm{As}$ $(x=0.032,$ 0.038, 0.047, 0.052, 0.058) of as-grown and low-temperature (LT) annealed samples are systematically studied using high-resolution Mn $2p$ absorption spectroscopy. The study exhibits coexistence of the ferromagnetic ${\mathrm{Mn}}^{2+}$ ion and the paramagnetic Mn-As complex that transforms into the ferromagnetic component with LT annealing. The ratio of ferromagnetic to paramagnetic components is directly related to the x dependence of the hole density and ferromagnetic critical temperature.