Abstract Due to the theoretical prediction of large tunneling magnetoresistance (TMR), graphene-based magnetic tunneling junction (MTJ) has become an important branch of high-performance spintronics device. In this paper, the non-collinear spin filtering and transport properties of MTJ with the Ni/tri-layer graphene/Ni structure were studied in detail by utilizing the non-equilibrium Green’s formalism combined with spin polarized density functional theory. The band structure of Ni–C bonding interface shows that Ni–C atomic hybridization facilitates the electronic structure consistency of graphene and nickel, which results in a perfect spin filtering effect for tri-layer graphene-based MTJ. Furthermore, our theoretical results show that the value of tunneling resistance changes with the relative magnetization angle of two ferromagnetic layers, displaying the anisotropic tunneling behavior of graphene-based MTJ. This originates from the resonant conduction states which are strongly adjusted by the relative magnetization angles. In addition, the perfect spin filtering effect is demonstrated by fitting the anisotropic conductance with the Julliere’s model. Our work may serve as guidance for researches and applications of graphene-based spintronics device.

中文翻译：

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基于石墨烯的磁隧道结中自旋输运的各向异性隧道行为

摘要 由于大隧道磁阻（TMR）的理论预测，石墨烯基磁隧道结（MTJ）已成为高性能自旋电子器件的一个重要分支。本文利用非平衡格林公式结合自旋极化密度泛函理论，详细研究了具有Ni/三层石墨烯/Ni结构的MTJ的非共线自旋滤波和输运特性。Ni-C 键合界面的能带结构表明 Ni-C 原子杂化促进了石墨烯和镍的电子结构一致性，从而为三层石墨烯基 MTJ 带来了完美的自旋过滤效果。此外，我们的理论结果表明，隧道电阻值随两个铁磁层的相对磁化角而变化，显示基于石墨烯的 MTJ 的各向异性隧道行为。这源于由相对磁化角强烈调节的谐振传导状态。此外，通过将各向异性电导与 Julliere 模型拟合，证明了完美的自旋过滤效果。我们的工作可以为基于石墨烯的自旋电子器件的研究和应用提供指导。