Surface half-metallicity and interfacial mixing of (Cr, Mn, Fe)VAs/GaAs(001)

We have investigated the magnetic and electronic properties of surface and interface for a mixed M(Ga,As) alloys with 1-2 monolayers (MLs) M(M = V, Cr, Mn, and Fe) on the GaAs(001) substrate by using first-principle calculations. We found that the surface and bulk V of zinc-blende VAs(001) half-metallic states result in diffierent lattice parameters. The surface V (or Cr) for the M-terminated zinc-blende M/As/M/GaAs(001) of 2-ML M shows a half-metallic character, while the gap in the minority-spin state of V (or Cr) in the third layer from the surface is destroyed. However, the hypothetical zinc-blende As/M/(GaM)/AsGa(001) with the surface diffusion of As atoms is found to be energetically favorable structure in the case of 2-ML M. The magnetism of V, Cr, or Mn for the 2-ML M system has the antiferromagnetic order, while for Fe it has the ferromagnetic order.