Improving the performances of PMNT crystals to enhance the responsivity of the magnetoelectric sensors with MPP structure via alternating current polarization

Abstract

Magnetoelectric (ME) sensors based on coupling principle of “magneto-mechano-electric” have drawn much attention in past few years. With further research, it is proved that the detection capability of the ME sensors with “multi-push-pull” (MPP) structure can reach to the current level of commercial fluxgate, showing a great application prospect in the fields of weak magnetic field detection. In this work, the alternating current polarization (ACP) method is the first to be applied to improve the ME response of ME composites with MPP structure. Poling conditions, including temperature, voltage and frequency, are well discussed in this paper. Moreover, the combination of finite-element simulations and experiments are employed to identify the optimal poling conditions. According to the PFM images, the improvement of piezoelectricity after ACP method may come from the high domain wall densities. Furthermore, two ME sensors with MPP structure prepared by the direct current polarization (DCP) method and the ACP method are compared. ME response in quasi-state condition and resonant condition are both improved, and equivalent magnetic noise (EMN) decreases from 4.07 pT/Hz1/2@1 Hz to 3.62 pT/Hz1/2@1 Hz after the ACP method, demonstrating a significant increase in detection capability.