Electric Polarization in ErCrO3 Induced by Restricted Polar Domains

Electric polarization in ErCrO3 single crystals has been investigated in the temperature range of 5_370 K. Ferroelectric ordering has not been found in any of the directions. However, electric polarization induced by restricted polar domains of structural origin has been observed. These domains are formed in the crystal matrix near impurity Bi^{3+} ions partially substituting Er^{3+} ions during the growth of single crystals by the method of spontaneous crystallization using solvent Bi_2O_3. The restricted polar domains form the superparaelectric state. Hysteresis loops with remanent polarization, both along the c axis and in the [110] directions, have been observed below some temperatures T_fr (in the frozen superparaelectric state). The polarization exists up to certain temperatures, which depend on the applied electric field orientation with respect to the crystal axes and exceed significantly temperature T_N of magnetic ordering.