Spin-polarized electronic structure and magnetic properties of Ge1−xTMxTe (TM=Mn, Fe)

• Ab-initio study of the magnetic properties of Ge1−xMnxTe and Ge1−xFexTe.
• Spin exchange splitting energies and exchange constants are predicted.
• Half-metallic behavior was observed for Ge1−xFexTe (x=0.125, 0.25).
• We found that Ge1−xMnxTe (x=0.125, 0.25) is a narrow gap semiconductor.

We have investigated the structural, electronic and magnetic properties for Ge1−xTMxTe (TM=Mn, Fe) in the rock-salt (RS) structure for (0≤x≤1). The calculations were performed using the full potential linearized augmented plane wave plus local orbitals method (FP-LAPW+lo) within the frame work of the density functional theory and the generalized gradient approximation (GGA). Structural properties are determined from the total energy calculations and results are given for the lattice parameters, bulk moduli and spin magnetic moments. The analysis of band structures and density of states reveals that for x=0.125 and x=0.25, GeMnTe is a narrow gap semiconductor and GeFeTe is a half metal while for x=0.5 and x=0.75 both alloys present a metallic character. Furthermore, we predict the values of spin exchange splitting energies Δx(d) and Δx(pd) and exchange constants N0α and N0β produced by the 3d Mn and 3d Fe states.