Enhanced Magneto-Mechanical Coupling with FeGaB/AlN Thin Films in Mesoscopic Silicon-Free Coupled-Structure Magnetoelectric Resonators

In conventional MEMS magnetoelectric (ME) sensors, the presence of a silicon substrate introduces extra mechanical stress and energy dissipation, hindering the direct and efficient coupling between the magnetostrictive and piezoelectric layers. In this case, we developed a silicon-free ME resonator design, featuring an asymmetric coupled cantilever beam structure, where one beam has a 200 nm FeGaB magnetic layer on a 1 μm AIN piezoelectric layer, while the other beam has only the piezoelectric layer. The hysteresis loop further indicates stable magnetic performance with a low energy loss of 83.56 J/m³. Dynamic characterization using laser Doppler interferometry reveals enhanced magneto-mechanical coupling of 367 ppm/Oe, especially at resonant frequencies around 65.35 kHz with a quality factor of 602 under atmospheric conditions. The absence of the Si substrate minimizes mechanical losses, amplifying the magneto-mechanical coupling, marking an improvement over Si-based counterparts. This ME design shows potential for high-precision positioning and magnetic imaging applications.