Ferromagnetism in heavily Fe-doped GaAs: a DFT study

Computational calculations based on density functional theory were carried out to investigate ferromagnetism in gallium arsenide (GaAs) heavily doped with Fe atoms that can substitutionally occupy gallium (Ga) or arsenic (As) sites in the zinc-blende-like crystal structure. The calculations were performed within the spin polarized density functional theory (DFT) and generalized gradient approximation (GGA) with full potential linearized augmented plane wave (FP-LAPW) method. We investigate and discuss the ab initio calculation results focusing on properties intrinsically important for spintronic applications, such as spin polarization and magnetic anisotropy. The density of states (DOS) was calculated with substitution of Fe atoms in the As and Ga sites, giving the electronic properties, as well as the magnetic ground state. According to DFT calculations, heavily doped GaAs with 25 at. % of Fe becomes a ferromagnetic metal with spin polarization as high as 69% at Fermi level. This is corroborated by experimental results previously published in literature.