Hydrogenation driven formation of local magnetic moments in FeO$_2$H$_x$

TL;DR

This study uses advanced computational methods to show that hydrogenation transforms FeO2 into a correlated metal with localized magnetic moments, significantly altering its electronic and magnetic properties relevant to Earth's lower mantle.

Contribution

It reveals how hydrogen addition induces local magnetic moments in FeO2H, a new mineral component, through destruction of O-O orbitals and increased electron correlation.

Findings

FeO2H is a correlated metal with mass renormalization ~2.

Hydrogenation localizes magnetic moments on Fe ions.

Electronic structure of FeO2H differs markedly from FeO2.

Abstract

The electronic and magnetic properties of recently discovered new important constituent of the Earth's lower mantle FeO2H were investigated by means of the density functional theory combined with the dynamical mean field theory (DFT+DMFT). Addition of the hydrogen to the parent FeO2 compound, which is an uncorrelated bad metal, destroys the most important ingredient of its electronic structure - O-O molecular orbitals. In effect physical properties of FeO2 and FeO2H turn to be completely different, FeO2H is a correlated metal with a mass renormalization, m*/m ~ 2, and magnetic moments on Fe ions become well localized with the Curie-Weiss type of uniform magnetic susceptibility.