Magnetodielectric Effect in a New Multiferroic Crystals of Tetraethylammonium Tetrahalogenocobaltate

The ferroelectric phase transition in tetraethylammonium tetrahalogenocobaltate [N(C 2 H 5 ) 4 ] 2 CoClBr 3 (TEACCB-3) solid solution was observed at $T_{\mathrm{c}}=258$ K. It manifests itself by a pronounced peak of the dielectric permittivity and arising of the spontaneous polarization. Besides, the sample was found to undergo a ferrimagnetic type ordering below 8 K which coexists with the ferroelectric one within the same temperature range. This allows to consider the investigated solid solution as a multiferroic material. Such a conclusion also is confirmed by the observed magnetodielectric effect – considerable change of the dielectric permittivity near the Curie point induced by the applied magnetic field. The magnetoelectric coupling first of all is connected with Co2+ ion.