Low magnetization and anisotropy in the antiferromagnetic state of undoped iron pnictides

TL;DR

This paper investigates the magnetic properties of undoped iron pnictides using a five-band model, revealing a low magnetization state due to orbital interactions that explains experimental observations.

Contribution

It introduces a detailed five-band model analysis showing how orbital anisotropy leads to low magnetization and anisotropic exchange in undoped iron pnictides.

Findings

Identification of a metallic low moment state with antiparallel orbital magnetic moments

Orbital anisotropy explains small magnetization and exchange anisotropy

Orbital ordering correlates with observed photoemission features

Abstract

We examine the magnetic phase diagram of iron pnictides using a five band model. For the intermediate values of the interaction expected to hold in the iron pnictides, we find a metallic low moment state characterized by antiparallel orbital magnetic moments. The anisotropy of the interorbital hopping amplitudes is the key to understanding this low moment state. This state accounts for the small magnetization measured in undoped iron pnictides and leads to the strong exchange anisotropy found in neutron experiments. Orbital ordering is concomitant with magnetism and produces the large zx orbital weight seen at Gamma in photoemission experiments.