Polar properties of Eu_0.6Y_0.4MnO₃ ceramics and their magnetic field dependence

Eu_1−xY_xMnO₃, compared against other magnetoelectric systems, exhibits very distinctive features. Its magnetoelectric properties are driven by the magnetic spin of the Mn³⁺ ion, but they can be drastically changed by varying the content of Y³⁺, which does not carry any magnetic moment. Although the x = 0.40 composition has been studied extensively, some basic areas still remain to be thoroughly understood. Thus, this work is aimed at studying some of its polar properties and their magnetic field dependence as well. The experimental results reported here show that this material is very easily polarizable under external electric fields, and so, whenever the polarization is obtained from time integration of the displacement currents, an induced polarization is superposed on the spontaneous one, eventually masking the occurrence of ferroelectricity.

We have found clear evidence for the influence of a magnetic field in the polar properties of Eu_0.6Y_0.4MnO₃. The study of electric polarization of Eu_0.6Y_0.4MnO₃ under an external magnetic field yields a value with the same order of magnitude of the remanent polarization as was determined from polarization reversal experiments. The comparison of the magnetically induced changes in the polarization obtained for polycrystalline samples and single crystals confirms the threshold magnetic field value for the polarization rotation from the a-direction to the c-direction, and provides evidence of the importance of the granular nature of the samples in the polar response to the magnetic field.