Magnetoelectric Coupling in Inorganic/Organic Hybrid Composite Thin Films

Magnetoelectric thin films can be used for various flexible electronics and biomedical applications but are limited by achieving strong magnetoelectric coupling at room temperature in a simple device. We report on the formation of a hybrid magnetoelectric system based on a new three-step grow-etch-fill process. First, a vertically aligned nanocomposite thin film containing a magnetostrictive CoFe₂O₄-based material and a sacrificial passive component (MgO) is grown. Then the MgO is etched out, to leave a mesoporous structure having 10’s nm dimensionality, and then a ferroelectric polymer PVDF-TrFE is coated onto the mesoporous structure.<br/><br/>Our study shows a novel approach to high-performance magnetoelectric composites. The films have advantages over previous composites of the same composition of having much higher density of interfaces for more effective strain coupling between the ferroelectric and magnetostrictive phases at directional, high-quality interfaces between the two materials. Also, the ability to more carefully tune and change the magnetic anisotropy in the CoFe₂O₄ films to design strong magnetoelectric coupling is demonstrated. The strain coupling and strain profile in these films were modelled using finite element analysis as a guideline to optimise the magnetoelectric effect in these films.