First principles calculations on electronic structure and magnetism of Fe/GaAs(001)

To investigate the electronic structure and magnetism of the Fe-GaAs interface, a first principles study has been done on the Fe atoms grown on the GaAs (001) surface, using the full potential linearized augmented plane wave method. To simulate the outward diffusions of Ga and As, the Fe subsurface systems were taken into account as well as the Fe overlayer ones. From total energy calculations, it is proved that the subsurface systems are much more stable compared to the overlayer ones. When Ga and As atoms diffuse out of the surface, the total energies of the systems were calculated to be lower by about 1380 and 1500 meV, respectively. The outward diffusion of As atoms leads the system to be stable in an antiferromagnetic state.