A magnetoelectric sensor of threshold DC magnetic fields.

A multiferroic magnetic field sensor capable of producing an output for threshold magnetic fields has been fabricated and characterized. The sensor consists of a trilayer composite of piezoelectric X-cut lanthanum gallium tantalate and magnetostrictive Metglas placed inside a solenoid and a wide-band amplifier. The composite plays two distinct roles in the device; it forms the feedback loop of an oscillator and sets the frequency of sustained oscillations. The sensor generated an output of 2.5V at the longitudinal acoustic resonance frequency of 87.5 kHz for the trilayer for DC magnetic fields H=0.3 to 50 Oe parallel to the composite plane. The device functions as a threshold magnetic field sensor for this H-interval, and the threshold ON and OFF H-values for an ac voltage output could be controlled electronically or with a proper choice of the ferromagnetic phase in the composite. [ABSTRACT FROM AUTHOR]