TMR与GMR传感器1/f噪声的研究进展

隧道结磁阻(TMR) 传感器及巨磁阻(GMR) 传感器的1/f噪声在低频段噪声功率密度较大, 是影响其低频下分辨率和灵敏度的主要噪声形式. 本文详细介绍了近年来TMR传感器及GMR传感器1/f噪声的特点、来源、理论模型、检测方法及降噪措施等方面的研究进展, 并就隧道结磁阻传感器1/f噪声的物理模型进行了详细解释. 通过纳米模拟软件Virtual NanoLab对不同MgO厚度的Fe/MgO/Fe型磁性隧道结(MTJ) 进行了隧穿概率和TMR变化率的模拟计算, 得到保守估计与乐观估计的TMR变化率, 分别为98.1%与10324.55%, 同时通过MTJ的噪声模型分析了MgO厚度对TMR传感器噪声的影响. 制备了磁屏蔽系数大于10000的磁屏蔽筒并搭建了磁阻传感器1/f噪声的测试平台, 通过测试验证了磁屏蔽系统对环境磁场具有较好的屏蔽效果, 为噪声检测提供了稳定的磁场空间. 最后分析了TMR与GMR中各种因素对传感器噪声的影响, 提出了影响MTJ传感器1/f噪声的因素及一些降噪措施.

Researching progress of the 1/f noise in TMR and GMR sensors

The low-frequency noise is the most important influence on the low frequency resolution and sensitivity in tunnel junction magnetoresistance(TMR) sensors and giant magnetoresistance (GMR) sensor for the large noise power density. In this paper, We describe the 1/f noise characteristics, sources, theoretical models, testing methods and noise reduction measures for TMR sensors and GMR sensors, and the detailed physical model of 1/f noise in the tunnel junction magnetoresistive sensor is explained. By nano-simulation software Virtual NanoLab, Fe/MgO/Fe magnetic tunnel junctions (MTJs) with different thicknesses of MgO layer are studied. Their tunneling probabilities and TMR change rates are simulated and calculated, the conservative and the optimistic estimates of the Change rate of TMR are 98.1 % and 10324.55%.While the influence of MgO thickness on noise is studied through the MTJ model. To study the noise dependance on external magnetic field, an magnetic shielding equipment for noise measurement is set up, and the tests show that the noise in the magnetic shielding environment is significantly reduced.