Magnetically Tuned Impedance and Capacitance for FeGa/PZT Bilayer Composite under Bending and Longitudinal Vibration Modes.

A magnetically tunable magnetoelectric transducer consisting of rectangular FeGa(FeGa)/Pb(Zr,Ti)O(PZT) composites is developed, and their magnetoimpedance and magnetocapacitance effects are investigated under bending and longitudinal modes. Specifically, the composites' impedance and capacitance are found to vary with dc magnetic field H, which results from the varied effective dielectric permittivity of the FeGa/PZT composite with H due to the delta E effect, magnetostrictive effect of FeGa and mechanism responsible for ME coupling between the FeGa and PZT layers. Furthermore, the FeGa/PZT bilayered composite exhibits both bending and longitudinal vibration modes due to the asymmetrical stress distributions. The maximum ΔZ/Z of the FeGa/PZT composite is about 215% at the antiresonance frequency = 28.78 kHz of the bending-mode, which is 2.53 times as high as that at the antiresonance frequency = 107.9 kHz of the longitudinal mode, while the maximum ΔC/C of the FeGa/PZT composite is about 406% at the resonance frequency = 28.5 kHz of the bending mode, which is 3.5 times as high as that at the antiresonance frequency = 106.6 kHz of the longitudinal mode. This study plays a guiding role for the design and corresponding application of magnetic sensors, magnetic-field-tuned electronic devices and multiple frequency ultrasonic transducers.