Magnetoelectric Coupling Springing Up in Molecular Ferroelectric: [N(C₂H₅)₃CH₃][FeCl₄]

A molecule-based ferroelectric triethylmethylammonium tetrachloroferrate(III) ([N(C₂H₅)₃CH₃][FeCl₄]) powder was designed as a multifunctional material exhibiting excellent multiple bistability. Prepared by the slow evaporation method at room temperature, the compound crystallizes in the non-centrosymmetric assembly of hexagonal symmetry (P6₃mc space group) which undergoes a reversible temperature-triggered phase transition pinpointed at 363 K to the centrosymmetric packing within the P6₃/mmc space group. Aside from the inseparable role of the symmetry-breaking process smoothly unveiled from the X-ray powder diffraction data, a striking change in the dielectric permittivity observed during the paraelectric-to-ferroelectric phase transition directly discloses the bistable dielectric behavior-an exceptionally high increase in the dielectric permittivity of about 360% at 100 kHz across the heating and cooling cycles is direct proof showing the highly desirable stimuli-responsive electric ordering in this improper ferroelectric architecture. Due to the magnetically modulated physical properties resulting in the coupling of magnetic and electric orderings, the flexible assembly of [N(C₂H₅)₃CH₃][FeCl₄] could be used to boost the design and development of novel magnetoelectric devices.