Pressure-Driven Metal-Insulator Transition in Hematite from Dynamical Mean-Field Theory

TL;DR

This study uses LDA+DMFT to investigate pressure-induced metal-insulator and spin transitions in hematite, revealing a volume collapse driven by electronic changes near 50 GPa.

Contribution

It applies LDA+DMFT to hematite to accurately model the simultaneous insulator-metal and spin transitions under pressure, providing insights into the electronic nature of the transition.

Findings

First-order insulator-metal transition at critical volume

High-spin to low-spin transition occurs concurrently

Transition associated with a volume collapse at ~50 GPa

Abstract

The Local Density Approximation combined with Dynamical Mean-Field Theory (LDA+DMFT method) is applied to the study of the paramagnetic and magnetically ordered phases of hematite Fe$_2$O$_3$ as a function of volume. As the volume is decreased, a simultaneous 1st order insulator-metal and high-spin to low-spin transition occurs close to the experimental value of the critical volume. The high-spin insulating phase is destroyed by a progressive reduction of the charge gap with increasing pressure, upon closing of which the high spin phase becomes unstable. We conclude that the transition in Fe$_2$O$_3$ at $\approx$50 GPa can be described as an electronically driven volume collapse.