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arXiv · 0901.3333

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

James M. Rondinelli·Aaron S. Eidelson·Nicola A. Spaldin
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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 $μ$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.

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James M. Rondinelli, Aaron S. Eidelson, Nicola A. Spaldin. 2009-01-21. Non-$d^0$ Mn-driven ferroelectricity in antiferromagnetic BaMnO$_3$. https://doi.org/10.1103/physrevb.79.205119

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