Theoretical modeling of detectivity of magnetoelectric magnetic sensor and ultra‐high magnetic detectivity of Metglas/PMNT/Metglas laminates

Abstract

In this paper, we proposed the detectivity of magnetoelectric (ME) device and charge mode sensor based on the response and noise models, and developed the detectivity figure of merits (FOMs). From the perspective of signal-to-noise ratio, the FOMs clarified the effect of permittivity and dielectric loss of ME material on the detectivity of sensor, and the interaction between the ME material and pre-amplification. According to the FOMs and guideline, we fabricated the push-pull mode of Metglas/PMNT/Metglas composite with high detectivity FOMs. After being coupled with a self-made charge amplifier, the sensor showed a high detection capability, as the noise equivalent magnetic induction (NEB) is only 5pT/Hz 1/2 at 1 Hz. A comparison between the calculated FOMs and the sensors performance further verified the validaty of the model. At last, we summarized some guidelines for the improvement of materials, structures of the device, and the operating conditions in the sight of detectivity.