Electric Polarization in ErCrO3 Induced by Restricted Polar Domains

Resumo

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 Bi³⁺ ions partially substituting Er³⁺ ions during the growth of single crystals by the method of spontaneous crystallization using solvent Bi₂O₃. 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. These temperatures correspond to the condition kT_fr ≈ E_A for activation barriers at the boundaries of the restricted polar domains.