Effect of Replacement of Fe2+ by Co2+ in W-Type Hexagonal Ferrite BaFe18O27 to its Electronic Properties from First Principles

Abstract

Using a model in which Fe at 6g sites is assumed to be partially replaced by Co, the electronic ground structure of BaCo2Fe16O27and the origin of the electrical conductivity have been studied within framework of the generalized gradient approximation (GGA) plus Hubbard U (GGA+U) calculation. Replacement of Fe at 6g site of BaFe18O27by Co causes the mixed valence states of Fe cations at 6g sites to vanish and the charge carrier density to lower. This is the main reason why both of materials reveal high electrical conductive anisotropy and the electrical resistivity of BaCo2-W is 103~104times higher than BaFe2-W.