Above-Room-Temperature Magnetodielectric Coupling in a Possible Molecule-Based Multiferroic: Triethylmethylammonium Tetrabromoferrate(III)

A possible above-room-temperature molecular multiferroic, triethylmethylammonium tetrabromoferrate(III) (1), has been discovered. Its ferroelectric and magnetic phase transitions take place at almost the same temperature (∼360 K), resulting in strong magnetodielectric (MD) coupling, with a MD ratio of 18% at 0.6 MHz. Interestingly, 1 also undergoes a low-temperature ferroelectric-ferroelectric phase transition with an Aizu notation of 6mmF6 and small magnetic and dielectric anomalies at 171 K.