Self-biased magnetoelectric charge coupling in transducer of SmFe₂, Pb(Zr,Ti)O₃ stack, and stepped horn substrate with multi-frequency effect

This paper presents a broadband, self-biased magnetoelectric (ME) charge coupling in a transducer comprising of a negative magnetostrictive SmFe₂ plate, a piezoelectric Pb(Zr,Ti)O₃ (PZT) stack, and a stepped horn substrate. By using the SmFe₂ plate with a large anisotropic field, an outstanding self-biased piezomagnetic effect is realized. The horn serves as a waveguide with multiple resonances and converges vibrating energy excited by the SmFe₂ plate from the wide side to the narrow side, which results in a higher vibrating magnification at the position of the PZT-stack. Then, a strong mechanical-electric coupling is realized by the use of the PZT-stack with high capacitance. Consequently, several large peaks of ME charge response with magnitudes of 1.02–18.99 nC/Oe in the 0.1–50 kHz range are observed at zero-biased magnetic field. This demonstrates that the proposed broadband self-biased structure may be useful for multifunctional devices such as low frequency AC magnetic field sensors or multi-frequency energy harvesters.