Magnetic properties of thin-film Fe–Pd alloy and magnetoelectric coupling in Fe–Pd/Ag/PZT/Ag/Fe–Pd laminate composites

Magnetoelectric (ME) coupling in multi-ferroic composite designed by Pb(Zr1−xTix)O3 (PZT) and ferromagnetic shape memory alloy Fe–Pd was investigated to apply to small magnetic sensor. Magnetostrictive Fe70Pd30 (3.5, 10 μm in thickness) films on both surfaces of PZT were deposited by a magnetron sputtering. On the other hand, rapidly solidified Fe70Pd30 (30 μm) ribbons were glued on both surfaces of PZT. The Fe70Pd30 films and the Fe70Pd30 ribbon consist of fct martensitic and fcc parent phases. When a driving ac magnetic field of frequency range of 0.07 Hz to 80 kHz and low dc bias magnetic field below 50 Oe were applied along the length by coil about the laminate composites, the ME charge generated across the samples was measured by charge amplifier. The output ME voltage VME of these Fe70Pd30–PZT laminate composites exhibited a very large peak at a resonant frequency of 61–68 kHz, and was constant in a low frequency range of 0.5–100 Hz. The VME values of these laminate composites increased with the stress constants g33 of PZT and the Fe70Pd30 film thickness.