MEMS RF Magnetoelectric FeGaB/Quartz Receivers.

Recent research work on the theoretical and experimental possibilities of acoustically actuated MEMS RF magnetoelectric antennas using piezoelectric-magnetostrictive multilayers have been published, for example in ref. [1], [2]. A mechanism of electromagnetic-acoustic coupling was achieved in the composite ferromagnetic/piezoelectric heterostructure. The magnetostrictive thin film provided the function of converting the RF magnetic signal to acoustic vibration of the composite resonator while the piezoelectric body realized the transduction of acoustic wave to electric signal. In this paper, we proposed a novel MEMS RF FeGaB/Quartz receiver sensor where FeGaB had a relatively stronger piezomagnetic coefficient compared to other ferromagnetic materials such as nickel. The quartz resonator had the advantages of high Q, low resistance, and high frequency-temperature stability. Experiments were set up to measure the remnant magnetization state of FeGaB thin film deposited on AT- and SC-cut quartz wafers. Consistent comparison results were obtained between the simulated and measured magnetization curves of FeGaB thin films. A 10 MHz AT-cut quartz resonator coated with 200-nm-thick FeGaB layer was fabricated and tested. The frequency response of a similar uncoated quartz resonator was also tested so that the difference between the responses of coated and uncoated resonator respectively could yield a qualitative view of the magnetic field response. A special setup of experiments were taken to reduce the electric field effect of the RF signal. The simulated frequency responses of the coated and uncoated resonators showed trends that were consistent with the experimental results.