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

TL;DR

This study uses first-principles calculations to analyze the electronic structure of the oxygen-free superconductor Ba1-xKxFe2As2, revealing its quasi-two-dimensional ionic metallic nature and potential magnetic or orbital fluctuation-driven pairing mechanisms.

Contribution

First-principles FLAPW-GGA calculations provide new insights into the electronic and magnetic properties of Ba1-xKxFe2As2, comparing it with the parent compound BaFe2As2.

Findings

Density of states at Fermi level increases with hole doping.

Ba1-xKxFe2As2 is classified as a quasi-two-dimensional ionic metal.

System is near magnetic instability, suggesting magnetic or orbital fluctuations may mediate pairing.

Abstract

Based on first-principles FLAPW-GGA calculation, we have investigated electronic structure of newly discovered oxygen-free 38K superconductor Ba1-xKxFe2As2 in comparison with parent phase - tetragonal ternary iron arsenide BaFe2As2. The density of states, magnetic properties, near-Fermi bands compositions, together with Sommerfeld coefficients and molar Pauli paramagnetic susceptibility are evaluated. The results allow us to classify these systems as quasi-two-dimensional ionic metals, where the conduction is strongly anisotropic, only happening on the (Fe-As) layers. According to our calculations, at the hole doping of BaFe2As2 the density of states at the Fermi level grows, and this can be a possible factor of occurrence of superconductivity for Ba1-xKxFe2As2. On the other hand, Ba1-xKxFe2As2 lays at the border of magnetic instability and the pairing interactions might involve magnetic or orbital fluctuations.