Design of magnetoelectric multiferroic heterostructures by topology optimization

Composite BaTiO3-CoFe2O4 nanostructures deposited on a SrTiO3 substrate are known to produce the magnetoelectric coupling effect. Although the coupling efficiency is significantly influenced by the composite layout, there appears no systematic simulation approach for configuring optimal layouts. In this study, a formulation to find optimal heterostructures using the topology optimization method is developed. For the formulation, the macroscopic extrinsic magnetoelectric coupling factor is maximized while numerical calculation is performed by finite element analysis. The proposed method yields an optimal piezoelectric and piezomagnetic material distribution. Numerical simulations are used to explain why the optimized distribution indeed maximizes the magnetoelectric coupling effect. As an application of the developed method, a magnetic read head sensor using the magnetoelectric effect is also designed.