Microelectromechanical magnetic field sensor based on ΔE effect

We present a fully integrated microelectromechanical magnetic field sensor based on the ΔE effect. The vacuum encapsulated sensor extends our previous approach [B. Gojdka et al., Appl. Phys. Lett. 99, 223502 (2011); Nature 480, 155 (2011)] and now involves an intermediate piezoelectric AlN layer between a SiO2 cantilever and a magnetostrictive FeCoBSi top layer. The AlN layer serves two functions: It drives the resonator, and it is used for electrical read out. The limit of detection was strongly enhanced to 12 nT/ Hz at 10 Hz.