Voltage-controlled manipulation of magnetization at the micro and nanoscale
The main goal of the project is to explore new energy-efficient ways to manipulate the magnetization state of composite multiferroic systems by an electric field. Magnetic micro- and nano-structures are patterned on top of a piezoelectric (like PMN-PT) or a ferroelectric (like BaTiO3) substrate, and their magnetic state is imaged while an electric field is applied through the thickness of the substrate. An efficient and reliable electric field-controlled magnetization rotation was observed in BaTiO3\CoFe nanostructures, making this materials system very interesting for application purposes. Furthermore, the magneto-elastic coupling in PMN-PT\Ni microstructures was directly revealed by imaging simultaneously the piezo-strain in the substrate and the magnetic state of the Ni microstructures in response to the applied electric field. This allows us to unveil the direct connect between the electrically induced strain and the resulting magnetic state.
Concept of a Magneto-Electric RAM cell. The application of a voltage through the BaTiO3 generates the motion of its ferroelectric domains, resulting in the rotation of the magnetization state of the nanostructure. See publication in Phys. Rev. Materials.
Unveiling the direct link between piezo-strain and magnetization in PMN-PT\Ni microstructures. The system consists of Ni microsquares on top of a piezoelectric PMN-PT single crystal substrate. By directly imaging both the electric field-induced reorientation of the magnetization in the Ni microsquares and the piezo-strain in the substrate right underneath the microstructures, allowed us to show the direct coupling between the two ferroic orders. As shown in the bottom of the figure, magnetic squares that needed a larger electric field to be reoriented were positioned on regions of the substrate where a smaller (in magnitude) piezo-strain was observed, and vice-versa. See publication in Nano Letters. Thsi work was highlighted by the Advanced Light Source and in Advances in Engineering.
