Influence of metglas layer on nonlinear magnetoelectric effect for magnetic field detection by frequency modulation

Linear magnetoelectric (ME) and nonlinear magnetoelectric effects are considered systematically in this paper. We have prepared 3 multi-push-pull magnetoelectric laminated composites Metglas/PMNT/Metglas with n layers metglas (n = 1, 2, and 3). When n increases from 1 to 3, the linear magnetoelectric charge coefficients increase from 1900 to 2200 and then to 2600 pC/Oe at 2 Hz under their each optimal magnetic bias. By using these 3 ME composites, we have also prepared 3 ME sensors, the sensitivity of which are as low as 130, 168, and 199 pT/√Hz at 1 Hz for n = 1, 2, and 3, respectively, via nonlinear modulation method. Therefore, the nonlinear ME charge coefficients decrease as layer numbers of metglas increase, which is different with the ME charge linear coefficient's increasing trend, also demonstrated coupled with the finite element analysis method. The factors that result in the higher nonlinear ME charge coefficient in ME composites with fewer metglas layers are analyzed and discussed in detail.