Engineering multiferroism in CaMnO$_3$

TL;DR

This study uses first-principles calculations to explore how strain and chemical modifications can induce multiferroicity in CaMnO$_3$, revealing that ferroelectricity and magnetism can coexist in this material.

Contribution

It demonstrates that CaMnO$_3$ can be engineered to exhibit multiferroic properties by leveraging its weak ferroelectric instability and cation-driven ferroelectricity.

Findings

CaMnO$_3$ has a weak ferroelectric instability.

Strain or chemical engineering can induce ferroelectricity.

Ferroelectricity is Mn-dominated, linking it to magnetism.

Abstract

From first-principles calculations, we investigate the structural instabilities of CaMnO$_3$. We point out that, on top of a strong antiferrodistortive instability responsible for its orthorhombic ground-state, the cubic perovskite structure of CaMnO$_3$ also exhibit a weak ferroelectric instability. Although ferroelectricity is suppressed by antiferrodistortive oxygen motions, we show that it can be favored using strain or chemical engineering in order to make CaMnO$_3$ multiferroic. We finally highlight that the FE instability of CaMnO$_3$ is Mn-dominated. This illustrates that, contrary to the common believe, ferroelectricity and magnetism are not necessarily exclusive but can be driven by the same cation.