Effect Of Magnetoelectric Effect On Magnetic And Electrical Transformation

With the development of the times and the progress of science and technology, people put forward more and more requirements for the electronic devices, especially in the miniaturization and integration for the devices, Nanomaterials and thin film promote the miniaturization of the devices. A main proach of the integration is to set several functions in one material, that is a kind of multiferroic materials-magnetoelectric composite, which is one of the hot topics and is born as the times requirement.This paper mainly discusses some problems about the magnetoelectric materials.Magnetoelectric composite ceramics of spinel ferrite Ni0.5Zn0.5Fe204(NZFO) with high magnetic permeability and tetragonal perovskite Pb(Zr0.48Ti0.52)03(PZT) with high piezoelectric constant were synthesized by common solid state reaction method. XRD and SEM showed that high dense composite ceramics without any foreign phases were obtained. The ceramics showed excellent dielectric and magnetic properties, which were stable in a large frequency range. The dielectric peak became wider with the ferrite content in the permittivity spectrum with temperature. With the increase in the ferrite content, the magnetic Curie temperature shifted to higher temperature and closed to that of the pure ferrite. In addition, the magnetoelectric coefficient enhanced as the increase in the ferrite content. The properties of the composite ceramics could be adjusted by the ferrite content.Magnetoelectric effects on ferromagnetic and ferroelectric phase transitions in multiferroic materials were researched experimentally and theoretically. The shifts of ferroelectric/ferromagnetic Curie point under magnetic/electric field were observed because of the magnetoelectric coupling in magnetoelectric composites. We employed Landau method with Gibbs free energy function including ferroelectric, ferromagnetic and magnetoelectric items to understand our experimental results and some recent reports. The numerical simulations presented some important conclusions, including the jumps of magnetization/polarization near the ferroelectric/ferromagnetic phase transition, shifts of Curie point under external fields. These calculations are coincident with the experimental results very well. The magnetoelectric limitation was also proved with this simple method. The results indicate that the parameters such as Curie temperature, polarization, magnetizaion and susceptibilities can be adjusted by the magnetic or electric field.At the end of this paper, we show the main conclusion of the Landau theory without considering the magnentoelectric coupling, which provide the necessary prior knowledge for understanding the effect of magnetoelectric coupling.