Magnetoelectric effect from mechanically mediated torsional magnetic force effect in NdFeB magnets and shear piezoelectric effect in 0.7Pb(Mg1∕3Nb2∕3)O3–0.3PbTiO3 single crystal

We experimentally and theoretically report the magnetoelectric effect in a composite made by sandwiching one shear mode 0.7PbMg1∕3Nb2∕3O3–0.3PbTiO3 (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 ∼32.7mV∕cmOe with a flat frequency response in the measured range of 0.1–30kHz. The induced magnetoelectric voltage shows a good linear relationship to the applied ac magnetic field with amplitude varying from 10−7to10−3T. 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.