Dual-resonance converse magnetoelectric and voltage step-up effects in laminated composite of long-type 0.71Pb(Mg_1/3Nb_2/3)O ₃-0.29PbTiO₃ piezoelectric single-crystal transformer and Tb_0.3Dy_0.7Fe_1.92 magnetostrictive alloy bars

We report a dual-resonance converse magnetoelectric effect and a dual-resonance voltage step-up effect in a laminated composite made by sandwiching the output (or secondary) section of a long-type 0.71Pb(Mg _1/3Nb_2/3)O₃-0.29PbTiO₃ (PMN-PT) piezoelectric single-crystal transformer having a longitudinal-longitudinal polarization between two Tb_0.3Dy_0.7Fe_1.92 (Terfenol-D) magnetostrictive alloy bars having a longitudinal magnetization. The reported converse magnetoelectric effect originates from the mechanically mediated resonance converse piezoelectric effect in the PMN-PT transformer and resonance converse magnetostrictive effect in the Terfenol-D bars. The additional voltage step-up effect results from the mechanically mediated resonance converse and direct piezoelectric effects in the PMN-PT transformer. The composite shows two sharp resonance peaks of 0.39 and 0.54 G/V in converse magnetoelectric coefficient (α_B dB/dV_in) and of 1.4 and 2.1 in voltage step-up ratio (V_out/V_in) at about 54 and 120 kHz, corresponding to the half- and full-wavelength longitudinal mode resonances, respectively. The measured magnetic induction (B) exhibits good linear relationships to the applied ac voltage (V_in) with amplitude varying from 10 to 100 V in both resonance and nonresonance conditions. These dual-resonance effects make the composite great promise for coil-free electromagnetic device applications.