Effect of Ni and Co impurities on the electronic structure and magnetic properties of BCC iron

A theory of disordered binary alloys A_xB_1−x (A=Ni, Co; B=Fe; x0.06) is used to determine the changes in the electronic structure and magnetic properties of body centered cubic (BCC) iron induced by doping with nickel and cobalt impurities. This approximation is an extension of the cluster-Bethe lattice method, in which we incorporate electronic correlations, itinerant and localized nature of electrons 3d, and both long-range and short-range chemical correlations. The magnetism is described by means of a Hubbard Hamiltonian that in conjunction with Green's functions techniques is used to calculate local densities of electronic states. For it we take an atom in the real lattice and it is joined to a Bethe's lattice with like coordination number. The magnetic moments on sites occupied for A and B atoms are obtained self-consistently. Nickel and cobalt impurities in BCC iron can provide crucial information on the modification of the electronic band structure and magnetic moments from pure Fe. The results obtained are compared with those of both pure Fe and binary alloys of Co–Fe and Ni–Fe, which have been obtained by other authors using methods such as: first-principles electronic structure calculations using the layer Korringa–Kohn–Rostoker (KKR), the full-potential linearized augmented plane wave method, the KKR coherent potential approximation combined with the local-density functional method and by the tight-binding linear-muffin-tin orbitals method, obtained good agree. These results and other that recently we have published indicate to us that our methodology can be a new alternative for calculations of the electronic structure and magnetic properties of impurities and alloys of ferromagnetic transition metals.