Linearization of the tunneling magnetoresistance sensors through a three-step annealing process

For tunneling magnetoresistance (TMR) sensors using magnetic tunnel junctions (MTJ), the sensor output linearization is of great importance for practical applications. The current study employs a three-step magnetic annealing procedure for linearizing the double-pinned MTJs, setting the magnetization of the free layer to be orthogonal to that of the reference layer. Compared to the traditional two-step annealing procedure, the three-step annealing procedure benefits from a lower annealing temperature and excellent linearity performance. Utilizing the three-step annealing procedure, the sensitivity and the detectivity of 1.57 mV/V/Oe and 29.3 nT Hz^0.5 @ 10 Hz, respectively, was achieved in a full Wheatstone bridge TMR sensor. Our results reveal a new pathway for linearization of the TMR sensors through three-step annealing process.