Electronic structure of new oxygen-free 38-K superconductor Ba1-xKxFe2As2 in comparison with BaFe2As2 from the first principles

Based on first-principle FLAPW-GGA calculations, we have investigated the electronic structure of the newly discovered oxygen-free 38-K superconctuctor Ba(1-x)K(x)Fe(2)As(2) in comparison with a parent phase - the tetragonal ternary iron arsenide BaFe(2)As(2). The density of states, magnetic properties, near-Fermi band compositions, together with the Sommerfeld coefficients gamma and the molar Pauli paramagnetic susceptibility chi have been evaluated. The results obtained allow us to classify these systems as quasi-two-dimensional ionic metals, where the conduction is strongly anisotropic, occurring only in the (Fe-As) layers. According to our calculations, in the case of the hole eloping of BaFe(2)As(2), the density of states at the Fermi level grows, which may be a factor promoting the occurrence of superconductivity for Ba(1-x)K(x)Fe(2)As(2). On the other hand, Ba(1-x)K(x)Fe(2)As(2) lies at the hordes of the magnetic instability and the pairing interactions might involve the magnetic or orbital fluctuations.