Lorentz magneto-resonator model and colossal magnetodielectric effect of magnetoelectric heterostructures

In the vicinity of their resonance frequency, magnetoelectric heterostructures, which are laminated magnetostrictive material with a piezoelectric resonator, are highly sensitive to external magnetic field. At room temperature colossal magnetodielectric effect near to 30,000% close to the electromechanical resonance frequency was obtained in a magnetic field of about 400 Oe. In this article we present a theoretical model for the magnetoelectric heterostructures based on the Lorentz magneto-resonator model. We show that the colossal magnetodielectric effect is related to the polarization direction of the piezoelectric resonator. When the direction of polarization is parallel to the direction of magnetostriction, the magnetodielectric effect of magnetoelectric heterostructures is much higher than that of the polarization direction perpendicular to the magnetostriction direction. The results of this model are in excellent agreement with experimental data. This modeling environment is found to be extremely useful for understanding how magnetoelectric heterostructures are working in various applications and how to design new magnetic-electric integrated resonant devices.