Magnetism and Superconductivity in the Two-Dimensional 16 Band d-p Model for Iron-Based Superconductors

TL;DR

This study models the electronic states of iron-based superconductors using a 16-band d-p model, revealing how magnetic and superconducting phases depend on Coulomb interactions and pairing symmetries.

Contribution

It introduces a detailed 16-band d-p model including Coulomb interactions and analyzes magnetic and superconducting phases using RPA, highlighting the dependence on Hund's coupling J.

Findings

Magnetic phase diagram includes stripe and incommensurate orders.

Superconducting pairing symmetry varies with Hund's coupling J.

Extended s-wave pairing occurs at large J, dxy-wave at small J.

Abstract

The electronic states of the Fe2As2 plane in iron-based superconductors are investigated on the basis of the two-dimensional 16-band d-p model which includes the Coulomb interaction on a Fe site: the intra- and inter-orbital direct terms U and U', the Hund's coupling J and the pair-transfer J'. Using the random phase approximation (RPA), we obtain the magnetic phase diagram including the stripe and the incommensurate order on the U'-J plane. We also solve the superconducting gap equation within the RPA and find that, for large J, the most favorable pairing symmetry is extended s-wave whose order parameter changes its sign between the hole pockets and the electron pockets, while it is dxy-wave for small J.