Ab initio electronic conductivity of Fe-bearing post-perovskite

TL;DR

This study uses advanced ab initio methods to evaluate the electronic conductivity of Fe-bearing post-perovskite under extreme conditions, finding it unlikely to become metallic in super-Earth mantles, thus impacting planetary interior models.

Contribution

It provides the first detailed ab initio analysis of Fe-bearing post-perovskite's conductivity at super-Earth mantle conditions, incorporating many-body effects and dynamical screening.

Findings

Post-perovskite remains insulating at super-Earth mantle conditions.

Electronic conductivity is negligible, unlike (Fe,Mg)O which metallizes.

Non-electronic conduction mechanisms may be necessary for high conductivity.

Abstract

The electrical conductivity of high-pressure silicates profoundly influences the interior dynamics of rocky planets. Employing the Kubo-Greenwood formalism, we perform ab initio calculations of electronic conductivity in Fe-bearing post-perovskite under super-Earth mantle conditions, up to 4000 K and 500 GPa. Electronic structures are obtained via many-body perturbation theory, incorporating dynamical screening and correlations among localized Fe-3d orbitals. In contrast to (Fe,Mg)O, for which metallization has been reported at comparable conditions, our results indicate that post-perovskite with Earth-like Fe contents is unlikely to metallize in super-Earth mantles via band-gap closure, yielding negligible low-frequency conductivity. Any substantial conductivity would require non-electronic mechanisms, such as thermally activated small-polaron hopping, which fall beyond the scope of band conduction.