Orbital Degeneracy and the Microscopic Model of the FeAs Plane in the Iron-Based Superconductors

TL;DR

This paper proposes a microscopic model emphasizing orbital degeneracy in FeAs planes, predicting antiferromagnetic order in parent compounds and d-wave superconductivity upon doping, highlighting the role of inter-orbital couplings.

Contribution

It introduces a new microscopic model focusing on orbital degeneracy, explaining magnetic and superconducting phases in iron-based superconductors.

Findings

Predicts antiferromagnetic order in parent compounds

Forecasts d-wave superconductivity at finite doping

Shows inter-orbital couplings enhance both orders

Abstract

A microscopic model for the FeAs plane in the newly discovered Iron-based superconductors is proposed with the emphasis on the role of the orbital degeneracy between the Fe $3d_{xz}$ and $3d_{yz}$ orbital in the crystal field environment. The model predicts commensurate antiferromagnetic ordered ground state for the parent compounds and a d-wave superconducting ground state at finite doping. Inter-orbital couplings plays an interesting role in enhancing both orders. Correlated variational wave functions are proposed for both ordered phases.