Enhancement of magnetoelectric effect in polymer composites at low resonance frequencies by operation in the transverse-transverse mode

The resonant direct magnetoelectric (ME) effect for a series of multilayer heterostructures comprising magnetoactive elastomer (MAE) of different thicknesses and commercially available piezoelectric polyvinylidene fluoride-based vibration sensor has been investigated in detail. The specimens were rigidly fixed at one end as cantilevers. The cantilevers were operated in the transverse-transverse (T-T) mode, where both magnetic and electric fields were perpendicular to the plane of a non-deformed heterostructure. It is shown that the ME voltage coefficient of considered heterostructures in the T-T mode can be about 20-fold higher than in the conventional longitudinal–transverse (L-T) mode. The highest ME voltage coefficient reached about 150 V/(Oe·cm) at the first bending oscillation mode for the sample with MAE layer thickness of 4 mm. Mechanism of the resonant ME effect in T-T mode is explained using theory of critical bending of MAE cantilevers. Magnetic fields, when the ME voltage reaches its maximum, strongly depended on the MAE layer thickness, and could be associated with the critical field, where the structure commences to strongly bend. The non-monotonous dependence of the resonance frequency of the first oscillation mode on magnetic field strength was observed. The shift of the resonance frequency in the maximum magnetic field reached up to roughly 100 % in comparison with zero field.