Theoretical study on self-biased magnetoelectric effect of layered magnetoelectric composites

By introducing a high permeability material into the traditional magnetoelectric (ME) composite, a non-zero ME coefficient can be obtained when the external DC magnetic field is zero. This is called the self-biased ME effect. In this system, the high permeability material can be regarded as a special ferromagnetic material. A magnetic field will be generated around it, which affects the internal magnetic field distribution of the ferromagnetic phase in the ME composite. In this paper, we consider the multi-field coupling characteristics of the ME composites, the non-linear characteristics of the individual component materials, and the mechanical and magnetic properties of the high permeability material, to develop a theoretical model for such self-biased ME effect. Then the finite element method is employed to solve the Maxwell equations for this complex problem. The developed theory is highlighted with a direct comparison with experiments that shows their close agreement. It is also demonstrated that, with the addition of the high permeability material, the self-biased ME coefficient can account for 47% of the maximum ME coefficient. This remarkable outcome, and the detailed distributions of the magnetic field, electric field, and elastic field inside ME structures are also presented in detail. Finally, the influence of temperature on the ME effect of the two structures was also studied, and the results showed that the higher the temperature, the smaller the ME coefficient of the structures.