Frozen Superparaelectric State of Local Polar Regions in GdMn 2 O 5 and Gd 0.8 Ce 0.2 MnO 5

A comparative study of the dielectric properties and electric polarization of multiferroics GdMn2O5 and Gd0.8Ce0.2MnO5 has been carried out in the temperature range 5–330 K. The polarization properties in the ferroelectric state that forms due to a charge ordering and exchange striction have been studied at T ≤ TC = 30 K. The properties of the restricted polar phase separation domains formed in the crystals containing ions Mn3+ and Mn4+ have been studied, too. These domains exhibit the electric polarization in the temperature range from 5 K to some temperatures Tf ≫ TC. Such a high-temperature polarization is due to the frozen superparaelectric state of the restricted polar domains.