The Analysis of Hysteresis in the Spin Valve Magneto-resistance

Since the measurement accuracy of the spin valve GMR (giant magneto-resistance) sensor is decreased significantly by the hysteresis, this paper deals with the influence of the pinning shape at the end of the free layer, the pinning angle, the pinned area, the free layer thickness and length on the hysteresis is investigated. Then the hysteresis curves of several kinds of sensor structures have been simulated with micro magnetic software. Finally, via the simulated result and the least square method, the coercivity and the linear range of the hysteresis have been calculated. This investigation shows that the length of the free layer is irrelevant to the coercivity. However, the pinning shape, the pinning angle, the pinned area, and the thickness of the free layer obviously affect the coercivity and the linear rang of the hysteresis. The results of this paper would facilitate the development of the spin valve GMR sensors with low hysteresis and wide linear range.