Magnetic sensors based on piezoelectric-magnetostrictive composites

Abstract Magnetoelectric (ME) composites have been fabricated by sandwiching a lead titanate (PZT) laminate between two magnetostrictive (Tb(Fe 0.55 Co 0.45 ) 1.5 ) (known as Terfecohan) films. Giant ME effect at low fields obtained is associated to large magnetostriction as well as high magnetostrictive susceptibility of the Terfecohan films. Magnetoelectric voltage coefficients, α E  = (∂ E /∂ H ), as large as 3350 and 9650 V m/kA m were achieved, respectively, for the as-deposited, and annealed films. The coefficient α E was, however, highly dependent on the direction of the magnetic field with respect to the electrical polarization. On the basic of this magnetoelectric composite, a magnetic sensor operating in an ac magnetic field of 0.1 mT at a resonant frequency of 40 Hz has been prepared. The ME voltage response in applied magnetic fields (d V ME /d H ) as large as 130 mV/mT was obtained.