Half-metallic Mn-doped Si(x)Ge(1 − x) alloys: a first principles study

First-principles pseudopotential calculations within density functional theory have been performed for Si(x)Ge(1 − x) alloys doped with Mn, focusing on the structural, electronic, and magnetic properties as a function of the composition of the host matrix and distribution of Mn atoms. Our results show that half-metallicity, typical of most diluted magnetic semiconductors, is very sensitive to the local environment around the Mn impurity: when Mn is surrounded by Ge atoms, half-metallicity is preserved for all the considered composition range, whereas it is generally lost when Si atoms are first-nearest-neighbors of the Mn impurity. Remarkably, the calculated formation energies show that a local Ge environment around Mn impurity should be favored over a Si local environment: therefore, these systems, along with the desired half-metallicity, hold promise for spintronics applications.