Eu-doping effects on the structural and multiferroic properties of YMn_(0.5)Cr_(0.5)O_3

摘要

Y_(1-x)Eu_x-Mn_(0.5)Cr_(0.5)O_3 (x = 0.1-1.0) oxides were synthesized in a polycrystalline form by a conventional solid-state reaction method. X-ray diffraction patterns revealed that the whole series of compounds featured a simple distorted perovskite structure with the orthorhombic space group Pbnm. With increasing Eu content, the shorter a and c axes increased, while the longest b axis changed little. The ferrimagnetic transition temperature T_N increased gradually to x = 0.8 before declining with a further increase in x. A clear correlation between T_N and the negative molecular field coefficient within the Cr~(3+) sublattice indicated that an antiferromagnetic exchange interaction between the Cr~(3+) cations plays a dominant role in the magnetic ordering. By reversing the sign of the poling field, the occurrence of electric polarization reversal at temperatures around T_N implied a possible multiferroic state in the samples. From the dielectric point of view, the disappearance of the dielectric constant anomaly at T_N might be related to the high AC conductivity of the samples, which is a common feature of orthochromites.