Magnetic resonance probing of ferroelectricity and magnetism in metal-organic frameworks

We employ electron paramagnetic resonance (EPR) of the spin probe Mn2+ to study the paraelectric - ferroelectric transition in Dimethylammonium Manganese Formate (DMMnF) and Mn2+-doped Dimethylammonium Zinc Formate (DMZnF), which are considered model metal - organic frameworks (MOF) with a Pb-free perovskite architecture. In DMMnF, we study the variation of the Mn2+ EPR line shape and intensity at the X-band (similar to 9.4 GHz) and over 80 to 300 K, and we show the absence of magnetoelectric coupling at the ferroelectric transition. At the antiferromagnetic transition in DMMnF, we detect a magnetoelectric coupling caused by weak ferromagnetism in the AFM phase. In DMZnF, EPR spectra of the Mn2+ probe combined with DFT show that the crystal field is predominantly determined by the Dimethylammonium (DMA(+)) cations.