A Differential Surface Acoustic Wave Magnetic Field Sensor With Temperature Compensation

Surface acoustic waves (SAW) magnetic field sensors are promising in magnetic field and electric current detection applications. Acoustic waves have different frequency-magnetic field responses when SAWs propagate along on the hard axis and easy axis of the magnetic film, respectively. Here, we theoretically investigate an integrated differential SAW magnetic field sensor that consists of two SAW resonators based on the $\mathbf{CoFeB}/\mathbf{SiO}_{2}/\mathbf{quartz}$ structure. By designing the angle between SAW propagation directions of two SAW resonators and the hard axis of the magnetic film, the magnetic field sensitivity of the SAW magnetic field sensor is improved theoretically. The thermal stability of the differential SAW magnetic field sensor is also improved. The results are beneficial for developing SAW magnetic field sensors with high sensitivities.