Tuning the Ferroelectric Polarization in a Multiferroic Metal-Organic Framework

We perform density functional theory calculations on a recently synthesized metal-organic framework (MOP) with a perovskite-like topology ABX(3), i.e., [CH3CH2NH3]Mn(HCOO)(3), 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 similar to 2 mu C/cm(2). 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 mu C/cm(2). 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.