Electronic Structure of Ni-Doped BaFe2−x Ni x As2 (x = 0, 1, 2) Superconductor in the Nonmagnetic and Magnetic States

Abstract

The spin configuration, equilibrium crystal structure, and electronic structure of BaFe 2−x Ni x As 2 (x = 0, 1, 2) have been investigated by using ab initio pseudopotential Quantum Espresso code in the generalized gradient approximation. The total energy of different Fe(Ni) spin configurations has been calculated to determine the ground state in each doping. The results show an antiferromagnetic order in x = 0.0 and a nonmagnetic state for x = 2.0. Equilibrium lattice and internal parameters for this system have been calculated and compared with the literature data. This study shows that the lattice parameters in the magnetic calculations have been improved relative to the nonmagnetic calculations in comparison to the experimental data. Electronic band structure, Fermi surfaces, and density of states of all doping have been calculated and discussed in detail. The band structure near the Fermi level and Fermi surfaces has been changed considerably by Ni doping. The density of states includes a sharp Fe(Ni)3d orbitals below the Fermi energy and hybridization of As4p and Fe(Ni)3d orbitals in the lower energies.