Cooperative effects of Coulomb and electron-phonon interactions in the two-dimensional 16-band d-p model for iron-based superconductors

TL;DR

This study explores how Coulomb and electron-phonon interactions jointly influence electronic states and superconductivity in a detailed 16-band model for iron-based superconductors, revealing various ordered phases and pairing symmetries.

Contribution

It demonstrates the cooperative effects of Coulomb and electron-phonon interactions on superconducting pairing symmetries and phase diagrams in a comprehensive 16-band model.

Findings

Charge fluctuations lead to s++ wave superconductivity when electron-phonon interaction dominates.

Magnetic fluctuations induce s+- wave superconductivity under strong Coulomb interactions.

Orbital fluctuations are enhanced by the cooperation of Coulomb and electron-phonon interactions, resulting in multiple superconducting states.

Abstract

We study the electronic states and the superconductivity in the two-dimensional 16-band d-p model coupled with A1g, B1g and Eg local phonons and obtain the rich phase diagram including the magnetic, charge and orbital ordered phases on the parameter plane of the Coulomb and electron-phonon interactions. When the electron-phonon interaction is dominant, the charge fluctuations induce the s++ wave superconductivity, while when the Coulomb interaction is dominant, the magnetic fluctuations induce the s+- wave superconductivity. Remarkably, the orbital fluctuations are enhanced due to the cooperative effects of the Coulomb and electron-phonon interactions and induce the s++ wave and the nodal s+- wave superconductivities.