Enhancement of the nonlinear magnetoelectric effect in a ferromagnet-piezoelectric heterostructure due to nonlinearity of magnetization

We describe theoretically and experimentally a previously unobserved mechanism for the induction of the nonlinear magnetoelectric response in ferromagnet-piezoelectric multiferroic composites. We show that contributions to the nonlinear magnetoelectric effects come not only from the nonlinearity of the magnetostriction coefficient on the dc magnetic field but also from the nonlinear hysteretic dependence of the magnetization of the magnetic phase within the composite. The nonlinearity of the magnetization leads to the self-generation of an additional ac magnetic field oscillating at twice the frequency of the excitation field. In turn, this leads to the strain-mediated activation of the piezocomponent, generating a voltage output response and doubling its frequency relative to that of the excitation field. For the PbZrTiO₃/FeBSiC test sample examined in this study, we determined that this mechanism is responsible for an additional contribution of ∼14% to the nonlinear magnetoelectric effect.