Room-temperature paramagnetoelectric effect in magnetoelectric multiferroics Pb(Fe1/2Nb1/2)O3 and its solid solution with PbTiO3

摘要

We have observed the magnetoelectric response at room temperature and abovein high-resistive ceramics made of multiferroic Pb(Fe1/2Nb1/2)O3 (PFN) andPFN-based solid solution 0.91PFN-0.09PbTiO3 (PFN-PT). The value of theparamagnetoelectric (PME) coefficient shows a pronounced maximum near theferroelectric-to-paraelectric phase transition temperature, T_C, and thendecreases sharply to zero for T>T_C. The maximal PME coefficient in PFN isabout 4x10(-18) s/A. The theoretical description of the PME effect, within theframework of a Landau theory of phase transitions allowing for realistictemperature dependences of spontaneous polarization, dielectric and magneticsusceptibilities, qualitatively reproduces well the temperature dependence ofthe PME coefficient. In particular, the Landau theory predicts the significantincrease of the PME effect at low temperatures and near the temperature of theparaelectric-to-ferroelectric phase transition, since the PME coefficient isequal to the product of the spontaneous polarization, dielectric permittivity,square of magnetic susceptibility and the coefficient quantifying the strengthof the biquadratic magnetoelectric coupling