Magnetoelectric coupling in ceramic of the Zn-doped CaBaCo4O7 pyroelectric ferrimagnet

Electric and magnetic properties of the CaBaCo3.97Zn0.03O7 ferrimagnet ceramic have been studied. For this magnetoelectric compound, thermally assisted transitions in the pyroelectric current, at different temperatures characteristic of the magnetic transitions, are evidenced even in the absence of electrical poling. This result, interpreted by taking into account the magnetostrictive nature of this cobaltite, is supported by P(H) magnetoelectric coupling measurements performed in the 48-70 K interval. The change of polarization sign induced by changing the polarity of the poling electrical field, not observed in crystals but in 114 ferrimagnetic ceramics, is explained by symmetry arguments related to the tetrahedral coordination of the cobalt cations. Thus, this new type of pyroelectric ferrimagnetic ceramics might offer novel ways to exploit the magnetoelectric coupling of these oxides.