Electron correlation and spin density wave order in iron pnictides

TL;DR

This paper investigates how electron correlations influence the electronic structure and spin density wave order in iron pnictides, emphasizing the importance of nonperturbative effects and Hund's coupling in stabilizing magnetic phases.

Contribution

It introduces a multiorbital Hubbard model with Gutzwiller projection to analyze correlation effects, revealing their critical role in stabilizing metallic SDW phases in pnictides.

Findings

Ordered moments depend strongly on Hund's coupling J.

Correlation effects are essential for SDW phase stability.

Fermi surface topology evolves with magnetic order and doping.

Abstract

We study the correlation effects on the electronic structure and spin density wave order in Fe-pnictides. Using the multiorbital Hubbard model and Gutzwiller projection, we show that nonperturbative correlation effects are essential to stabilize the metallic spin density wave phase for the intermediate correlation strengths appropriate for pnictides. We find that the ordered moments depend sensitively on the Hund's rule coupling $J$ but weakly on the intraorbital Coulomb repulsion $U$, varying from $0.3\mu_B$ to $1.5\mu_B$ in the range $J=0.3\sim0.8$ eV for $U=3\sim4$ eV. We obtain the phase diagram and discuss the effects of orbital order and electron doping, the evolution of the Fermi surface topology with the ordered moment, and compare to recent experiments.