DC magnetic field sensor based on electric driving and magnetic tuning in piezoelectric/magnetostrictive bilayer

Abstract

A dc magnetic field sensor possessing an interestingly high electric voltage-driven, magnetic field-tuned dc magnetoelectric (ME) effect is developed based on a bilayer of Pb(Zr, Ti)O3 piezoelectric transformer and Tb0.3Dy0.7Fe1.92 magnetostrictive substrate. The dc ME effect in the sensor, as evaluated experimentally and theoretically, is induced by driving the bilayer at its zero-field longitudinal resonance frequency (fr0) using an ac electric voltage (Vac) referenced at the input of the piezoelectric transformer, as well as, by tuning the field-dependent compliance and resonance characteristics of the bilayer with the dc magnetic field to be measured (Hdc) upon the negative-ΔE effect intrinsic in the magnetostrictive substrate. The sensor shows a good linear negative response of ac ME voltage (VME) at the output of the piezoelectric transformer to a broad range of Hdc of 0-350 Oe under a small Vac of 2.5 V peak at the designated fr0 of 125.3 kHz. This gives a high negative dc magnetic field sensitivity (S) of -1.58 mV/Oe.