Analysis of Noise in Magnetoelectric Thin-Layer Composites Used as Magnetic Sensors

Taking advantage of magneto-elasto-electric interactions, new laminated composites of magnetostrictive and piezoelectric layers have been developed for highly sensitivity magnetoelectric (ME) sensors. The ME sensor design chosen in this study was based on long-type Metglas composites laminated together with piezoelectric fibers. In this paper, we analyze the expected limit of the magnetic noise of ME sensor versus its intrinsic characteristics and electronic setup. Theory calculations and experimental results are compared, and are well supported by noise measurements. Moreover, the presented results show very impressive performances in terms of the equivalent magnetic sensor noise. A 65
$\ {\rm pT}/\surd{\rm Hz}$
equivalent magnetic noise was achieved at 1 Hz, while reaching values as low as 70
${\rm fT}/\surd{\rm Hz}$
near the ME resonant frequency.