Ab initio study of electronic structure and magnetic properties in ferromagnetic Be1-xMnxSe and Be1-xMnxTe alloys

Structural, electronic and magnetic properties of Mn-doped BeSe and BeTe have been studied by employing the full-potential linear augmented plane waves plus local orbitals (FP-LAPW+lo) method within the spin-polarized density functional theory (DFT). The investigations are carried out by varying the Mn concentration, x, in BeSe and BeTe host matrices for x=0.25, 0.5 and 0.75. The results of spin-polarized calculations manifest the presence of ferromagnetic band structures with both spin-up and spin-down alignments. Our calculated results of band structures reveal that for x=0.25, 0.5 and 0.75, Be1-xMnxSe has a half-metallic (HM) band structure profile showing 100% spin polarization at the Fermi level. On the other hand, the Be1-xMnxTe band structure shows complete 100% spin polarization at the Fermi level only for x=0.25 and 0.5. Spin-dependent charge densities have been calculated to study the bonding nature, and the values of the exchange constants, N-0 alpha and N-0 beta, are also determined which are consistent with the values from the typical magneto-optical experiment. In addition, the calculations of spin exchange splitting, Delta(x)(d), exhibit important indication regarding the attractive effective potential for minority spin rather than majority spin. For each concentration x, the value of total magnetic moment has been estimated to be 5(mu B), which reveals that addition of Mn impurity does not affect the hole concentration of a perfect BeSe (Te) crystal. (c) 2013 Elsevier B.V. All rights reserved.