Effects of Amplitude and Frequency of the Modulation Field on the Sensitivity for Low-Frequency Magnetic Field in Magnetoelectric Sensors

Magnetoelectric (ME) sensors based on piezoelectric/ferromagnetic composites have been investigated extensively due to their resonance-enhanced ME coupling effect and high sensitivity for magnetic field, especially at resonant frequency. However, the sensitivity drops rapidly when the frequency drifts away from resonance, making it unsuitable for low-frequency applications. Frequency modulation has been proposed as an effective method to up-convert the frequency of the desired signal into the mechanical resonance. In this work, we study the optimized amplitude and frequency of the modulation field, which improve the sensitivity at low frequency by two orders of magnitude without increasing the noise level. Magnetic field of 200 pT is detected at 10 Hz with a near-flat frequency response in the range of 1-100 Hz, showing promising potential for low-frequency applications in smart grid and renewable energy.