Importance of the many-body effects for structural properties of the novel iron oxide: Fe$_2$O

TL;DR

This study demonstrates that many-body effects significantly influence the phase stability and transition pressures of the novel iron oxide Fe$_2$O, altering previous DFT predictions and highlighting the importance of advanced modeling methods.

Contribution

It reveals how many-body effects, especially magnetic fluctuations, critically impact the structural phase diagram of Fe$_2$O, which was not captured by standard DFT calculations.

Findings

Hubbard repulsion minimally affects electronic spectrum

Many-body effects lower critical pressures for phase transitions

DFT+DMFT shows instability of certain structures due to magnetic fluctuations

Abstract

The importance of many-body effects on electronic and magnetic properties and stability of different structural phases was studied in novel iron oxide - Fe$_2$O. It was found that while Hubbard repulsion hardly affects the electronic spectrum of this material ($m^*/m \sim 1.2$), but it strongly changes its phase diagram shifting critical pressures of structural transitions to much lower values. Moreover, one of the previously obtained in the density functional theory (DFT) structures (P$\bar 3$m1) becomes energetically unstable if many-body effects are taken into consideration. It is shown that this is an account of magnetic moment fluctuations in the DFT+DMFT approach, which strongly contributes to modification of the phase diagram of Fe$_2$O.