A study of hysteresis reduction of small ac magnetic field modulated tunneling magnetoresistive sensor

In this study, a hysteresis reduction technique for tunneling magnetoresistive (TMR) sensor for low magnetic field sensing is proposed, where a small ac modulation magnetic field is applied. The magnetic tunnel junctions were connected into an asymmetric Wheatstone bridge to form a sensor, and the output voltage of the TMR sensor was measured using a small ac modulation field and test field along the sensor’s sensing direction. The results showed that hysteresis in the TMR sensor can be effectively reduced to exhibit a linear response. Further, the frequency response of the TMR sensor was studied. Finally, the feasibility of the TMR sensor for low-field detection with small ac modulation was demonstrated.