Non-$d^0$ Mn-driven ferroelectricity in antiferromagnetic BaMnO${}_3$

Abstract

Using first-principles density functional theory we predict a ferroelectric ground state -- driven by off-centering of the magnetic Mn${}^{4+}$ ion -- in perovskite-structure BaMnO${}_3$. Our finding is surprising, since the competition between energy-lowering covalent bond formation, and energy-raising Coulombic repulsions usually only favors off-centering on the perovskite $B$-site for non-magnetic $d^0$ ions. We explain this tendency for ferroelectric off-centering by analyzing the changes in electronic structure between the centrosymmetric and polar states, and by calculating the Born effective charges; we find anomalously large values for Mn and O consistent with our calculated polarization of 12.8 $\mu$C/cm${}^2$. Finally, we suggest possible routes by which the perovskite phase may be stabilized over the usual hexagonal phase, to enable a practical realization of a single-phase multiferroic.

6 pages, 3 figures

References in corpus (1)

• Frustration of tilts and A-site driven ferroelectricity in KNbO_3-LiNbO_3 alloys

Cited by in corpus (1)

• Striped Multiferroic Phase in Double-Exchange Model for Quarter-Doped Manganites