Orbital Selective Pressure-Driven Metal-Insulator Transition in FeO from Dynamical Mean-Field Theory

TL;DR

This study uses LDA+DMFT calculations to investigate the pressure-induced metal-insulator transition in FeO, revealing an orbital-selective transition where only certain orbitals become metallic, aligning with experimental observations.

Contribution

First LDA+DMFT study of FeO's magnetic and spectral properties under pressure, demonstrating an orbital-selective metal-insulator transition consistent with experiments.

Findings

FeO is a Mott insulator at ambient pressure with high-spin Fe 3d states.

High-pressure transition reproduces experimentally observed metal-insulator change.

Transition is orbital selective, affecting only t2g orbitals while eg remain insulating.

Abstract

In this Letter we report the first LDA+DMFT (method combining Local Density Approximation with Dynamical Mean-Field Theory) results of magnetic and spectral properties calculation for paramagnetic phases of FeO at ambient and high pressures (HP). At ambient pressure (AP) calculation gave FeO as a Mott insulator with Fe 3$d$-shell in high-spin state. Calculated spectral functions are in a good agreement with experimental PES and IPES data. Experimentally observed metal-insulator transition at high pressure is successfully reproduced in calculations. In contrast to MnO and Fe$_2$O$_3$ ($d^5$ configuration) where metal-insulator transition is accompanied by high-spin to low-spin transition, in FeO ($d^6$ configuration) average value of magnetic moment $\sqrt{<\mu_z^2>}$ is nearly the same in the insulating phase at AP and metallic phase at HP in agreement with X-Ray spectroscopy data (Phys. Rev. Lett. {\bf83}, 4101 (1999)). The metal-insulator transition is orbital selective with only $t_{2g}$ orbitals demonstrating spectral function typical for strongly correlated metal (well pronounced Hubbard bands and narrow quasiparticle peak) while $e_g$ states remain insulating.