Spin-pair correlation dependent dynamic properties in magnetic relaxor ferroelectrics

Abstract

In magnetic relaxor ferroelectrics, for the coupling interaction between the relaxor ferroelectricity and magnetic order, the dielectric constant exhibits a sharp increase around the magnetic phase-transition temperature. Based on the consideration that a polarization process is associated with the thermally activated flips of the polar regions, the reorientable polar regions have the main contribution for the dielectric behavior. Considering the specialty of relaxor ferroelectrics, a distribution function for the relaxation times is introduced to simulate the dielectric behavior of the magnetic relaxor ferroelectrics. It is indicated that the dielectric anomaly below the magnetic phase-transition temperature is attributed to the fact that the activation energy against dipole reorientation is amended by the spin-pair correlation via the magnetoelectric coupling. The obtained real part of dielectric constants and the magnetocapacitance are in good agreement with the experimental results.