We present first-principles results on the electronic and magnetic properties of the cubic bulk β-phase of iron(III) oxide (Fe2O3). Given that all Fe-Fe magnetic couplings are expected to be antiferromagnetic within this high-symmetry crystal structure, the system may exhibit some signature of magnetic frustration, making it challenging to identify its magnetic ground state. We have analyzed the possible magnetic phases of the β-phase among which there are ferrimagnets, altermagnets and Kramers antiferromagnets. While the α-phase is an altermagnet and the γ-phase is a ferrimagnet, we conclude that the magnetic ground state for the bulk β-phase of Fe2O3 is a Kramers antiferromagnet, moreover, we find that close in energy there is a bulk d-wave altermagnetic phase. We report the density of states and the evolution band gap as a function of the electronic correlations, for suitable values of the Coulomb repulsion the system is a charge-transfer insulator with an indirect band gap of 1.5 eV. As the opposite to the γ-phase, the magnetic configuration between first-neighbor of the same kind is always antiferromagnetic while the magnetic configuration between Fea and Feb is ferro or antiferro. In this magnetic arrangement, first-neighbor interactions cancel out in the mean-field estimation of the N\'eel temperature, leaving second-neighbor magnetic exchanges as the primary contributors, resulting in a N\'eel temperature lower than that of other phases. Our work paves the way toward the ab initio study of nanoparticles and alloys for the β-phase of Fe2O3.
@article{arxiv.2412.03237,
title = {Ab-initio study of the beta Fe2O3 phase},
author = {Priyanka Mishra and Carmine Autieri},
journal= {arXiv preprint arXiv:2412.03237},
year = {2024}
}