Ab-initio prediction of magnetoelectricity in infinite-layer CaFeO2 and MgFeO2

TL;DR

This study uses density functional simulations to predict and enhance magnetoelectric effects in layered iron oxides CaFeO2 and MgFeO2, highlighting their potential for room-temperature applications.

Contribution

It provides the first ab-initio predictions of magnetoelectricity in CaFeO2 and introduces MgFeO2 as an optimized system with stronger polarization effects.

Findings

CaFeO2 exhibits large electric polarization controlled by magnetic order

MgFeO2 shows enhanced polarization due to structural distortion

Both materials demonstrate potential for room-temperature magnetoelectric applications

Abstract

Density functional based simulations are employed to explore magnetoelectric effects in iron-based oxides, showing a unique layered structure. We theoretically predict CaFeO2 to be a promising magnetoelectric, showing magnetically-controlled large electric polarization, possibly even above room temperature. The cross coupling between magnetic and dipolar degrees of freedom needs, as main ingredients, Fe-site spin-orbit coupling and a spin-dependent O p - Fe d hybridization, along with structural constraints related to the non-centrosymmetric point group and the peculiar geometry characterized by "flattened" FeO4 tetrahedrons. In order to enhance magnetoelectric effects, we performed a materials-design leading to a novel and optimized system, MgFeO2, where the larger O4 tetrahedral distortion leads to a stronger polarization.