Hund's coupling and electronic anisotropy in the spin-density wave state of iron pnictides

TL;DR

This paper investigates how Hund's coupling influences electronic anisotropy and orbital order in the spin-density wave state of iron pnictides, revealing a robust anisotropy near a specific Hund's coupling value.

Contribution

It provides a detailed analysis of Hund's coupling effects on electronic anisotropy and orbital order in iron pnictides' SDW state, highlighting a stable anisotropy regime.

Findings

Drude-weight anisotropy is robust near J ≈ 0.25U.

Ferro-orbital order increases with Hund's coupling J.

Orbital-weight distribution explains anisotropy behavior.

Abstract

In the multiband systems, Hund's coupling ($J$) plays a significant role in the spin and charge excitations. We study the dependence of electronic anisotropy on $J$ in terms of Drude-weight along different directions as well as the orbital order in the four-fold symmetry broken spin-density wave state of iron pnictides. A robust behavior of the Drude-weight anisotropy within a small window around $J \sim 0.25U$ with $U$ as intraorbital Coulomb interaction is described in terms of orbital-weight distribution along the reconstructed Fermi surfaces. We also find that the ferro-orbital order increases with $J$ in the widely accepted regime for the latter, which is explained as a consequence of rising exchange field with an increase in magnetization.