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 0.7PbMg(1/3)Nb(2/3)O(3)-0.3PbTiO(3) (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 similar to 32.7 mV/ cm 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. (C) 2008 American Institute of Physics.