The half-metallicity of zinc-blende CaC/GaAs(001) heterojunction: A density functional theory study

First principles calculations, based on spin density functional theory (SDFT) as implemented in the PWscf code of the QUANTUM-ESPRESSO package, are performed to study electronic and magnetic properties of CaC/GaAs(001) heterojunction. We simulate the interface of CaC in Zinc-Blende (ZB) structure and GaAs semiconductor to see whether this electrode could be a good choice for spin current injection or not. For this purpose, we calculate the spin-polarized density of states for ZB-CaC, in-plane strained ZB-CaC (tetragonal phase) and also for ZB-CaC/GaAs(001) heterojunction. It is shown that ZB-CaC, is a half-metal ferromagnet with large half-metallic gap. The half-metallicity is found to be robust with respect to the lattice deformation to the tetragonal phase and is maintained in the range of 0.59 < c/a < 1.22. Calculations with supercell scheme for simulation ZB-CaC/GaAs(001) heterojunction show that the spin polarization at the Fermi energy reduced at the CaC/GaAs(001) heterojunction. But due to large difference of density of states of spin channels around the Fermi energy, the spin polarization is large yet. So the CaC/GaAs(001) heterojunction can be used in spintronics applications as a spin current injector but it is not 100% spin-polarized. (C) 2012 Elsevier B.V. All rights reserved.