Inverse tunnel magnetoresistance in magnetic tunnel junctions with an Fe4N electrode
Inverse tunnel magnetoresistance in magnetic tunnel junctions with an Fe4N electrode
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DOI：
10.1063/1.2753576
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发表时间：
2007-07
影响因子：
3.2
通讯作者：
K. Sunaga;M. Tsunoda;K. Komagaki;Y. Uehara;M. Takahashi
中科院分区：
文献类型：
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作者：
K. Sunaga;M. Tsunoda;K. Komagaki;Y. Uehara;M. Takahashi
在室温下研究了Fe_4N_scinMgO_scinCoFeB和Fe/MgO/CoFeB磁性隧道结（MTJ）的磁输运性质。在Fe/MgO/CoFeB-MTJ中，观察到正常的隧道磁电阻（TMR）效应和大致对称的偏置电压（VB）依赖性，类似于表现出相干隧穿的MTJ，例如Fe/MgO/Fe。另一方面，在Fe4N scinMgO scinCoFeB-MTJ中观察到反向TMR效应，平行磁化结构的隧道电阻比反平行结构的隧道电阻高，并且TMR比对VB的依赖性很强.在VB = − 200 mV时获得的最大TMR幅度为18.5%，其中电流从Fe4N流向CoFeB。在VB = − 200 mV附近，反TMR比的增强是由于Fe4N和CoFeB磁化的反平行结构中隧道电导的宽峰。体相Fe_4N的少数自旋电子在费米能级+300 meV处的态密度峰值可能是这一现象的起源。
The magnetotransport properties of Fe4N∕MgO∕CoFeB and Fe/MgO/CoFeB magnetic tunnel junctions (MTJs) were investigated at room temperature. In the Fe/MgO/CoFeB-MTJ, normal tunnel magnetoresistance (TMR) effect and roughly symmetric bias voltage (VB) dependence were observed, similar to the MTJs exhibiting coherent tunneling such as Fe/MgO/Fe. On the other hand, the inverse TMR effect, showing higher tunnel resistance for parallel magnetization configuration than for antiparallel configuration, and strong asymmetric VB dependence of TMR ratio were observed in the Fe4N∕MgO∕CoFeB-MTJ. The maximum TMR magnitude of 18.5% was obtained at VB=−200 mV, where the current flows from Fe4N to CoFeB. The enhancement of the inverse TMR ratio around VB=−200 mV is due to the broad peak of tunnel conductance in antiparallel configuration of Fe4N and CoFeB magnetizations. A large peak of the density of state at +300 meV from the Fermi level for minority spin electrons of bulk Fe4N might be an origin of this phenomenon.