Measurement and simulation of magnetoelectric response in tri-layer polymer-based composites

Magnetoelectric (ME) materials which possess both magnetic and electric properties are of great interest for their potential applications in numerous devices such as magnetoelectric sensors for detecting AC or DC fields, energy harvesting systems, memory devices (magnetoelectric random access memory), transducer in microwave electronics. They can exhibit dielectric polarization induced by the magnetic field, a magnetization under an electric field. A strong ME effect requires the simultaneous presence of magnetic moments and electric dipoles. In this work, three phase composites are prepared from β phase Polyvinylidene fluoride (PVDF) and polyurethane (PU) based composites. The two following configurations were studied. They differ by the ferromagnetic or diamagnetic character of the particles added to the polyurethane: PU + 2%wt ferromagnetic Fe₃O₄ / PVDF / PU + 2%wt Fe₃O₄ (PVDF/ferro PU) and PU + 10%wt diamagnetic Bi₂O₃ / PVDF / PU + 10%wt Bi₂O₃ (PVDF/dia PU). The bi-stretched PVDF monolayer sample is used to evaluate the role of the magnetostrictive layer on the magnetoelectric current. The variation of the ME current versus the bias magnetic induction, and the phase between the current and the magnetic induction, suggests the existence of two types of ME coefficients and the complex nature of them. A simple model was used to represent the magnitude of the current and the phase shift, and the experimental and modeled data are in good agreement. The biggest linear ME coefficient was obtained with multilayers prepared with diamagnetic particles. Concerning the bilinear ME coefficient, the largest value was obtained for the system with ferromagnetic particles. The PVDF monolayer also showed a magnetoelectric effect due to the eddy current. These results open perspectives for the fabrication of specific materials with adapted ME coefficients.