Effect of second-order magnetic anisotropy on nonlinearity of conductance in CoFeB/MgO/CoFeB magnetic tunnel junction for magnetic sensor devices
Effect of second-order magnetic anisotropy on nonlinearity of conductance in CoFeB/MgO/CoFeB magnetic tunnel junction for magnetic sensor devices
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DOI：
10.1038/s41598-019-53439-0
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发表时间：
2019-11
影响因子：
4.6
通讯作者：
Takahiro Ogasawara;M. Oogane;M. Al-Mahdawi;M. Tsunoda;Y. Ando
中科院分区：
文献类型：
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作者：
Takahiro Ogasawara;M. Oogane;M. Al-Mahdawi;M. Tsunoda;Y. Ando
研究了二阶磁各向异性对磁隧道结线性电导输出的影响。在实验上，CoFeB/MgO/CoFeB基MTJ的制造，和非线性，NL进行了评估，为不同的厚度，从电导的CoFeB自由层的。在Hd= 1.0kOe的动态范围内，随着波长从1.5nm增加到2.0nm，最大NL、NLmax从1.86%减小到0.17%。为了理解这种NL行为的起源，构建了基于Slonczewski模型的理论模型，其中NL被证明取决于Hk 2/Hk 2的归一化二阶磁各向异性场和Hk 2/Hk 2/Hk 2的归一化二阶磁各向异性场。|赫夫|和Hd/|赫夫|.这里，Hkeff、Hk 2是MTJ中的自由层的有效和二阶磁各向异性场。值得注意的是，实验NLmax作为Hk 2/|赫夫|和Hd/|赫夫|FMR技术测得的结果与模型预测的结果相吻合。根据这些实验和计算，我们得出结论：Hk 2是NL的起源，并对NL的大小有很大影响。这一发现为我们理解NL提供了指导，并为线性输出MTJ传感器通过Hk 2控制传感特性开辟了新的前景。
We studied the effect of second-order magnetic anisotropy on the linear conductance output of magnetic tunnel junctions (MTJs) for magnetic-field-sensor applications. Experimentally, CoFeB/MgO/CoFeB-based MTJs were fabricated, and the nonlinearity, NL was evaluated for different thicknesses,tof the CoFeB free layer from the conductance. As increasingtfrom 1.5 to 2.0 nm, maximum NL, NLmaxwas found to decrease from 1.86 to 0.17% within the dynamic range,Hd= 1.0 kOe. For understanding the origin of such NL behavior, a theoretical model based on the Slonczewski model was constructed, wherein the NL was demonstrated to be dependent on both the normalized second-order magnetic anisotropy field ofHk2/|Hkeff| and the normalized dynamic range ofHd/|Hkeff|. Here,Hkeff,Hk2, are the effective and second-order magnetic anisotropy field of the free layer in MTJ. Remarkably, experimental NLmaxplotted as a function ofHk2/|Hkeff| andHd/|Hkeff|, which were measured from FMR technique coincided with the predictions of our model. Based on these experiment and calculation, we conclude thatHk2is the origin of NL and strongly influences its magnitude. This finding gives us a guideline for understanding NL and pioneers a new prospective for linear-output MTJ sensors to control sensing properties byHk2.