Anisotropy of the electrical conductivity in W-type hexagonal ferrites BaFe18O27 and BaCo2Fe16O27 from first principles

► We perform the first principles calculation of BaFe2-W and BaCo2-W. ► We propose a model of the crystal structure of hexagonal ferrites BaCo2-W. ► We find the mixed valence states at 6g sites of Fe cations in BaFe2-W. ► The doping of Co at 6g sites in BaFe2-W leads the mixed valence states to vanish. ► Both materials have anisotropies in the densities and effective mass of carrier.