Search

Some magnetoelectric sensors require predefined external magnetic fields to satisfy optimal operation depending on their resonance frequency. While coils commonly generate this external magnetic field, a microelectromechanical systems (MEMS) resonator integrated with permanent magnets could be a possible replacement. In this proof-of-concept study, the interaction of a MEMS resonator and the ME sensor is investigated and compared with the standard approach to achieve the best possible sensor operation in terms of sensitivity. The achievable sensor sensitivity was evaluated experimentally by generating the magnetic excitation signal by a coil or a small-sized MEMS resonator. Moreover, the possibility of using both approaches simultaneously was also analysed. The MEMS resonator operated with 20Vppat 1.377 kHz has achieved a sensor sensitivity of 221.21mV/T. This sensitivity is comparable with the standard approach, where only a coil for sensor excitation is used. The enhanced sensitivity of 277.0mV/T could be identified by generating the excitation signal simultaneously by a coil and the MEMS resonator in parallel. In conclusion, these MEMS resonator methods can potentially increase the sensitivity of the ME sensor even further. The unequal excitation frequency of the MEMS resonator and the resonance frequency of the ME sensor currently limit the performance. Furthermore, the MEMS resonator as a coil replacement also enables the complete sensor system to be scaled down. Therefore, optimizations to match both frequencies even better are under investigation.

The microscopic structure of Fe‐based metallic glasses (Fe80Ga20)88B12$\left(\left(\right. \left(\text{Fe}\right)_{80} \left(\text{Ga}\right)_{20} \left.\right)\right)_{88} \left(\text{B}\right)_{12}$ (FeGaB) and (Fe90Co10)78Si12B10$\left(\left(\right. \left(\text{Fe}\right)_{90} \left(\text{Co}\right)_{10} \left.\right)\right)_{78} \left(\text{Si}\right)_{12} \left(\text{B}\right)_{10}$ (FeCoSiB) is investigated during in situ thermal annealing using extended X‐ray absorption fine structure spectroscopy (EXAFS) above the Fe–K and Co–K absorption edges. FeGaB exhibits a phase transition above 450 °C, changing from amorphous glass to a partially crystalline structure. Its medium‐range structure after this transition is modeled from crystalline α‐Fe and FeGa3$\left(\text{FeGa}\right)_{3}$ reference structures, combined with amorphous nearest‐neighbor (NN) contributions of Fe2B$\left(\text{Fe}\right)_{2} \text{B}$. Local order in the glass phase is described with the same model, restricted to NN interactions. Changes in the amorphous structure occur at annealing temperatures which coincide with typical observations of changes in magnetic behavior. Meanwhile, in FeCoSiB, the EXAFS response is highly different between the Fe–K and Co–K absorption edges. EXAFS oscillations on the Fe edge are strongly suppressed, as opposed to the Co edge which shows typical amplitudes. Limited resolution in this data set allows modeling only in the first amorphous shell, based on the NN distances from FeCo. The cause of the two materials’ different EXAFS behavior at Fe–K despite similar iron content and identical experimental conditions is currently unknown and subject of further investigation. [ABSTRACT FROM AUTHOR]