Electrically controlled spin polarization and selection in a topological insulator sandwiched between ferromagnetic electrodes
Electrically controlled spin polarization and selection in a topological insulator sandwiched between ferromagnetic electrodes
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DOI：
10.1063/1.4861743
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发表时间：
2014-01
影响因子：
3.2
通讯作者：
Junjie Guo;W. Liao;He-ping Zhao;Guanghui Zhou
中科院分区：
文献类型：
--
作者：
Junjie Guo;W. Liao;He-ping Zhao;Guanghui Zhou
利用Keldysh非平衡格林函数的方法，从理论上研究了夹在铁磁电极之间的二维拓扑绝缘体（TI）中边缘态狄拉克电子的可控自旋极化和选择效率。观察到拓扑边缘态几乎完全的自旋极化，巨大反转约80%，远高于先前报道的值。此外，在调频电极平行结构调制下，自旋向上电子的选择效率首次大于95%，而在反平行情况下，自旋向下电子在宽能量范围内的选择效率高于90%，这主要是由于自旋隧道效应引起的后向散射和自旋消相效应。所得结果可为进一步了解TI边缘状态提供依据，并为基于TI设计高开关速度和高选择效率的自旋开关和滤波器提供有价值的指导。
We theoretically investigate the electrically controllable spin polarization and selective efficiency of the edge state Dirac electron in a two-dimensional topological insulator (TI) sandwiched between ferromagnetic (FM) electrodes by using the method of Keldysh nonequilibrium Green's function. A nearly full spin polarization of the topological edge state with giant inversion of ∼80% is observed, which is much higher than the value previously reported. Moreover, the selective efficiency for spin-up electrons under the modulation of the parallel configuration of FM electrodes has been demonstrated to be larger than 95% for the first time, while that for spin-down electrons in the antiparallel case is higher than 90% in a wide energy range, owing to the inter-edge spin tunneling induced backscattering and spin dephasing effect. The obtained results may provide a deeper understanding of the TI edge states and a valuable guidance to design spin switch and filter with high on-off speed and selective efficiency based on TIs.