Engineering multiferroism in CaMnO$_3$

Understand

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.