Is the nature of magnetic order in copper-oxides and in iron-pnictides different?

TL;DR

This paper compares the magnetic ordering mechanisms in copper-oxides and iron-pnictides using first-principles calculations, revealing that iron-pnictides' magnetic moments are small due to orbital frustration rather than itinerant behavior.

Contribution

It demonstrates that both magnetic states can be explained within a unified theoretical framework, challenging the view that iron-pnictides have itinerant magnetism.

Findings

Different super-exchange interactions in copper-oxides and iron-pnictides.

Magnetic moments in iron-pnictides are small due to orbital frustration.

Both magnetic ground states can be understood with the same theory.

Abstract

We use the results of first-principles electronic structure calculations and a strong coupling perturbation approach, together with general theoretical arguments, to illustrate the differences in super-exchange interactions between the copper-oxides and iron-pnictides. We show that the two magnetic ground states can be understood in a simple manner within the same theoretical foundation. Contrary to the emerging view that magnetic order in the iron-pnictides is of itinerant nature, we argue that the observed magnetic moment is small because of frustration introduced by the electrons of the Fe orbitals as they compete to impose their preferred magnetic ordering.