Experimental and theoretical evidence for pressure-induced metallization in FeO with the rock-salt type structure

TL;DR

This study provides experimental and theoretical evidence that FeO with a rock-salt structure becomes metallic under high pressure and temperature, driven by a spin crossover, without undergoing a structural phase change.

Contribution

It combines high-pressure experiments with first-principles calculations to demonstrate pressure-induced metallization in FeO without structural transition.

Findings

FeO metallizes at around 70 GPa and 1900 K

Metallization occurs without a structural phase transition

Spin crossover is linked to the metallization process

Abstract

Electrical conductivity of FeO was measured up to 141 GPa and 2480 K in a laserheated diamond-anvil cell. The results show that rock-salt (B1) type structured FeO metallizes at around 70 GPa and 1900 K without any structural phase transition. We computed fully self-consistently the electronic structure and the electrical conductivity of B1 FeO as a function of pressure and temperature, and found that although insulating as expected at ambient condition, B1 FeO metallizes at high temperatures, consistent with experiments. The observed metallization is related to spin crossover.