Electronic structure and Phase Stability of low-temperature Ba(Fe1-xNix)(2)As-2 Superconductor

To understand the electron doping effect into the parent compound BaFe2As2, we have theoretically evaluated phase stability and electronic structure of low temperature nickel (Ni) doped Ba(Fe(1-x)N(i)x)(2)As-2 superconductor. The optimized Fmmm phase are calculated by first principles pseudopotential and plane wave calculations within generalized-gradient approximation (GGA) with Perdew-Perke-Ernzerhof (PBE) exchange correlation functional. Our results show that nonmagnetic (NM) and antiferromagnetic (AFM) state having anisotropic spin configuration in the band structure calculation. This finding shows that a clear gap is observed in the band structure upon optimally Ni doping in the NM state with a small indirect gap 43.68 meV is found in the direction of G-X points. A spin gap 47.8 meV is obtained when a spin polarized orbital calculation is introduced to the system. The hybridization of Fe/Ni-3d and As-4p in the density of states (DOS) results a metallic region near the Fermi level and flat bands exist below the level. We suggest the observation provides a crucial understanding in the superconductivity of the materials.