Tuning the Ferroelectric Polarization in a Multiferroic Metal–Organic Framework

We perform density functional theory calculations on a recently synthesized metal–organic framework (MOF) with a perovskite-like topology ABX<sub>3</sub>, i.e., [CH<sub>3</sub>CH<sub>2</sub>NH<sub>3</sub>]­Mn­(HCOO)<sub>3</sub>, and predict a multiferroic behavior, i.e., a coexistence of ferroelectricity and ferromagnetism. A peculiar canted ordering of the organic A-cation dipole moments gives rise to a ferroelectric polarization of ∼2 μC/cm<sup>2</sup>. Starting from these findings, we show that by choosing different organic A cations, it is possible to tune the ferroelectric polarization and increase it up to 6 μC/cm<sup>2</sup>. The possibility of changing the magnitude and/or the canting of the organic molecular dipole opens new routes toward engineering ferroelectric polarization in the new class of multiferroic metal–organic frameworks.