Reduced resonance frequency and enhanced coupling coefficient in fishtailing magnetoelectric resonator

Reducing the resonance frequency of the first-order longitudinal vibration mode for a bulk magnetoelectric (ME) resonator has been a challenge for very low frequency (VLF) magnetic sensing and transmitting application. In this work, we design and fabricate a fishtailing ME resonator that reduces the anti-resonance frequency from 18.8 to 12.2 kHz and the resonance frequency from 18.2 to 11.5 kHz compared with conventional 1-1 typed resonator. Meanwhile, a significant enhancement of the resonant ME coupling coefficient [from similar to 8271 to similar to 11 400 V/(cm Oe)] is also realized. Finite element simulation and lumped mass method are used to calculate and analyze the principles of the reduced resonance frequency and the reasons for enhanced coupling performance. The geometry tailoring method in this work is believed to inspire applications of the resonant ME effect at very low frequency.