First principle study of alloys Ge1-xMnxTe and Ge1-xFexTe

In our work we have calculated the electronic and magnetic structural properties of the Ge1-xTMxTe alloy (MT=Mn, Fe) in the NaCl structure for concentrations (0 x 1), which was carried out using the liniarized plane wave method(FP-LAPW+lo) based on density functional theory(DFT) and we used the GGA approximation. The structural properties (a, B, B') are determined from the total energy, and our results are in good agreement with other calculations. Analysis of the band structure and density of state for a concentration of x=0.125 and x=0.25 showed that GeMnTe is a narrow-gap semiconductor, whereas GeFeTe is a half-metal. For concentrations x=0.5 and x=0.75 both alloys have a metallic character. In addition, we have predicted the exchange and separation energies Deltax(d) and Deltax(pd) and the exchange constants N0 and N0beta are produced by the 3d Mn and 3d Fe states.Key words: DFT, FPLAPW, Ferromagnetism, Magnetic moment, spin separation energies.