Spin currents and magnetoresistance of graphene-based magnetic junctions
Spin currents and magnetoresistance of graphene-based magnetic junctions
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DOI：
10.1140/epjb/e2009-00034-6
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发表时间：
2009-02
期刊：
影响因子：
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通讯作者：
A. Saffarzadeh;M. Ghorbani Asl
中科院分区：
文献类型：
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作者：
A. Saffarzadeh;M. Ghorbani Asl
采用紧束缚近似和非平衡绿色函数方法，研究了平面磁结中的相干自旋相关输运，该结由两个铁磁（FM）电极组成，电极被锯齿形或扶手椅形界面的石墨烯片（GF）隔开。结果表明，电子传导强烈地依赖于GF和FM电极之间的接触几何形状。在锯齿形界面的情况下，结表现出自旋阀效应与高磁阻（MR）的比率，并显示负微分电阻功能的一个单一的自旋通道在正的栅极电压。在扶手椅界面的情况下，电流-电压特性在低偏置电压下线性表现，因此，两个自旋通道都处于低MR比的开启状态。
Using the tight-binding approximation and the nonequilibrium Green’s function approach, we investigate the coherent spin-dependent transport in planar magnetic junctions consisting of two ferromagnetic (FM) electrodes separated by a graphene flake (GF) with zigzag or armchair interfaces. It is found that the electron conduction strongly depends on the geometry of contact between the GF and the FM electrodes. In the case of zigzag interfaces, the junction demonstrates a spin-valve effect with high magnetoresistance (MR) ratios and shows negative differential resistance features for a single spin channel at positive gate voltage. In the case of armchair interfaces, the current-voltage characteristics behave linearly at low bias voltages and hence, both spin channels are in on state with low MR ratios.