Phase separation in (Ga,Mn)As layers obtained by ion implantation and subsequent laser annealing

In this paper, we present the results of studies of the spectral, temperature, and field dependences of the transversal Kerr effect in Ga$_{1-x}$Mn$_{x}$As ($x$ = 0.0066–0.033) layers produced by ion implantation and subsequent pulsed laser annealing. The complicated nonmonotonous nature of the temperature dependences of the transversal Kerr effect and its dependence on the measurement range indicate a magnetic inhomogeneity of the layers. The reasons for the inhomogeneity can be the Gaussian distribution of Mn over the thickness of the layers and the electron phase separation in them. The appearance of new features in the spectra of the transversal Kerr effect is explained by the presence in the doped semiconductor matrix of nanoregions with a higher carrier concentration and a higher Curie temperature and a shift of the Fermi level into the valence band leading to an increase in the energy of optical transitions.