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 Tc=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 Co
²⁺
ion.