The dynamics of polarization and magnetization: Susceptibilities of magnetoelectric multiferroic heterostructure

The dynamic susceptibility is the crucial parameter of a material, especially when the material is needed to be applied in the electromagnetic applications. In this report, we discuss the magnetic and the electric susceptibilities of a magnetoelectric (ME) multiferroic heterostructure comprised of ferromagnetic (FM) and ferroelectric (FE) materials. Since the magnetoelectric couplings in multiferroic heterostructure have only existed at the interface between FM and FE, then the equation of motions in each lattice in every layer of FM and FE should be considered. The equations of motion in each lattice are solved simultaneously by employing entire-cell effective medium approximation. In numerical calculation, the parameters appropriate for Fe and BaTiO₃ are used. We found that interfacial ME couplings shift down the resonance frequency for both FM and FE susceptibilities. We also noticed that the addition of the number of FE or FM layer, which raises the number of interface between FE and FM affects the susceptibility curves. (paper)