Prediction and Optimization of Linearity of MTJ Magnetic Sensors Based on Single-Domain Model

In the fabrication of linear magnetic tunnel junction (MTJ) sensors, the utilization of magnetic bias field along the easy-axis direction makes the response of MTJ nonlinear, and the Néel and magnetostatic coupling usually induces a strong interlayer coupling field along the hard-axis direction. In this paper, we investigated the influence of hard-axis and easy-axis bias fields on the linearity of MTJ magnetic sensor. The prediction and optimization of linearity were done by applying an appropriate hard-axis bias field in the specific easy-axis bias field and the practical tunnel magneto-resistance (TMR) ratio, and the model was verified by experiments. This paper can give guidance to improve the linearity and to maximize the practical TMR ratio of the MTJ sensors under a given linearity requirement.