Magnetoelectric effect from mechanically mediated torsional magnetic force effect in NdFeB magnets and shear piezoelectric effect in 0.7Pb (Mg _1/3Nb_2/3)O₃-0.3PbTiO₃ single crystal

We experimentally and theoretically report the magnetoelectric effect in a composite made by sandwiching one shear mode 0.7Pb Mg13 Nb23 O3 -0.3PbTi O3 (PMN-PT) piezoelectric single crystal plate between two longitudinally magnetized NdFeB permanent magnet bars along the length direction of the PMN-PT plate. The magnetoelectric effect originates from the mechanically mediated product effect of the torsional magnetic force effect in the NdFeB bars and the shear piezoelectric effect in the PMN-PT plate. The composite exhibits a magnetoelectric voltage coefficient of ∼32.7 mVcm Oe with a flat frequency response in the measured range of 0.1-30 kHz. The induced magnetoelectric voltage shows a good linear relationship to the applied ac magnetic field with amplitude varying from 10-7 to 10-3 T. Other distinct features include no need to have a magnetostrictive phase, low Joule heating loss, and high scale-down capability. These suggest promising applications of the torsional-shear mode composite in power-free magnetic field sensors.