Voltage-controllable magnetic behavior in PZT/NiFe/CoFe nanocomposites

Recently, the electric field induced manipulation of magnetic properties has become one of the most interesting research topics because of its promising applications in magnetoelectronics, such as future logic elements and electric-magnetic memories. In this paper, the NiFe/CoFe ferromagnetic nanostructured thin films were directly deposited on the ferroelectric PZT substrate, which was polarized parallel to the thickness or along the surface. In these samples, the stress originating from the piezoelectric layer is transferred into the magnetostrictive layer, which induces an elastic strain and results in a change in magnetization, thanks to the converse magnetoelectric effect. By analyzing the magnetization of the nanocomposite under a fixed magnetic field up to 5̃103 Oe at different voltages applied to the ferromagnetic substrate, we can investigate the voltage-controllable magnetization in this composite. The obtained results show that the magnetization of the NiFe/CoFe film changes around 6% at the low voltage of 60V and up to two times larger at 800V in an external magnetic field of 50Oe. The use of voltage also allows the reversible adjustment of the magnetization orientation in ferromagnetic layers. © 2011 Vietnam Academy of Science & Technology.