Optimization of indirect magnetoelectric effect in thin-film/substrate/piezoelectric-actuator heterostructure using polymer substrate

Indirect magnetoelectric effect has been studied in magnetostrictive-film/substrate/piezoelectric-actuator heterostructures. Two different substrates have been employed: a flexible substrate (Young's modulus of 4 GPa) and a rigid one (Young's modulus of 180 GPa). A clear optimization of the indirect magnetoelectric coupling, studied by micro-strip ferromagnetic resonance, has been highlighted when using the polymer substrate. However, in contrast to the rigid substrate, the flexible substrate also leads to an a priori undesirable and huge uniaxial anisotropy which seems to be related to a non equibiaxial residual stress inside the magnetostrictive film. The strong amplitude of this non equibiaxiallity is due to the large Young's modulus mismatch between the polymer and the magnetostrictive film which leads to a slight curvature along a given direction during the elaboration process and thus to a large magnetoelastic anisotropy.