Electronic properties and magnetism of iron at the Earth's inner core conditions

TL;DR

This study uses advanced simulations to explore the electronic and magnetic properties of different iron phases under Earth's core conditions, revealing significant correlation effects and persistent magnetism that could influence Earth's magnetic field.

Contribution

It provides new insights into the stability and magnetic behavior of iron phases at extreme conditions using state-of-the-art ab initio methods with dynamical mean-field theory.

Findings

Non-Fermi liquid behavior in bcc Fe at core conditions

Presence of local magnetic moments at high temperature and pressure

High magnetic susceptibility in all phases supports geodynamo stability

Abstract

We employ state-of-the-art ab initio simulations within the dynamical mean-field theory to study three likely phases of iron (hexogonal close-packed, hcp, face centered cubic, fcc, and body centered cubic, bcc) at the Earth's core conditions. We demonstrate that the correction to the electronic free energy due to correlations can be significant for the relative stability of the phases. The strongest effect is observed in bcc Fe, which shows a non-Fermi liquid behaviour, and where a Curie-Weiss behaviour of the uniform susceptbility hints at a local magnetic moment still existing at 5800 K and 300 GPa. We predict that all three structures have sufficiently high magnetic susceptibility to stabilize the geodynamo.