Near-Flat Self-Biased Magnetoelectric Response in Three-Phase Metglas/Terfenol-D/PZT-Laminated Composites

The magnetoelectric (ME) response without bias is investigated in a three-phase Metglas/Terfenol-D/PZT (MTP)-laminated composite. The internal magnetic field induced by the differences in the magnetic properties of Terfenol-D (Tb_1-xDy_xFe_2-y) and Metglas (Fe₈₀Si₉B₁₁) and the stress coupling effect of Terfenol-D and Metglas contribute to the self-biased ME effect with a wide range of dc-bias responses. By adjusting the number of the Metglas layers, it is able to control the magnitudes of the self-biased ME voltage coefficient and the bending resonance frequency. The experimental results show that: 1) the resonant ME voltage coefficient for the MTP composite with three Metglas layers (L = 3) achieves 1.28 V/Oe (16 V/cm Oe) at zero bias, which is ~3.02 times higher than that of the Terfenol-D/PZT composite; 2) the ME response for the MTP composite is insensitive to the varying dc bias in the range of 0~800 Oe; 3) as the number of Metglas layers increases, the bending resonance frequency gradually increases and the self-biased ME voltage coefficient first increases and then decreases afterward; and 4) it can detect a weak magnetic field of H_ac = 3.87 × 10^-8 T using a lock-in amplifier with a 0.001 Vrms resolution. These results present the possibility of implementing an MTP composite in the self-biased magnetic sensor with small size and high performance.