Electric-field-induced magnetization reversal in 1–3 type multiferroic nanocomposite thin films

Abstract

Using a general Landau free-energy thermodynamic theory for ferroelectric (FE) and ferromagnetic (FM) phases, we investigate the magnetoelectric coupling effect on epitaxial 1–3 type multiferroic nanocomposite thin films. By taking into account the electrostrictive and magnetostrictive effects and the elastic stress arising from the FE/FM and film/substrate interfaces, we renormalize the dielectric and magnetic coefficients twice and obtain the quasi-intrinsic magnetoelectric coupling in Landau free-energy function of this multiferroic system. Then, the electrical-field-induced magnetization and polarization for different thicknesses of film in 1–3 type BaTiO3–CoFe2O3 nanocomposite system are analyzed. Our results show that an applied electric field can result in the reversal of magnetization in step with the switching of the electric polarization due to the out-of-plane elastic coupling between the interfaces of FE and FM phases, while the relaxation of the in-plane compressive stress of the thin film makes magnetization M and polarization P both decrease with increasing film thickness. These results are completely consistent with experimental ones.