Investigation of Piezomagnetism in Nickel Ferrite

Applications of magnetostrictive materials, such as sensors and energy-harvesting devices, generally involve the use of the dynamic deformation, i.e., the piezomagnetic effect, induced by an exciting magnetic field H
_ac
. However, this effect is rarely measured directly but commonly approximated by the strain derivative ∂λ/∂H, which is deduced from the quasi-static magnetostrictive curve. In this article, we propose an investigation of the piezomagnetic effect in nickel ferrite by directly measuring the dynamic magnetostriction under various exciting fields using a dynamic strain-gauge setup. These values are compared with the strain derivative in order to disclose the limitations thereof. In addition, the magnetoelectric effect is measured in a ferrite/PZT bilayer and compared with the calculated magnetoelectric coefficient based on an analytical model. When the dynamic magnetostrictive coefficients are integrated into the calculation, good accuracy is found with experimental values, whereas it is not the case for calculated coefficients based on the strain derivatives. The findings of the present study highlight the importance of accurately characterizing the piezomagnetic effect in magnetostrictive materials in order to optimize their performances in dynamic applications.