Observation of quantum-tunnelling-modulated spin texture in ultrathin topological insulator Bi2Se3 films
Observation of quantum-tunnelling-modulated spin texture in ultrathin topological insulator Bi2Se3 films
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DOI：
10.1038/ncomms4841
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发表时间：
2014-05-01
影响因子：
16.6
通讯作者：
Hasan, M. Zahid
中科院分区：
文献类型：
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作者：
Neupane, Madhab;Richardella, Anthony;Hasan, M. Zahid
了解超薄拓扑绝缘子膜中边界模式的自旋文字行为对于功能性纳米版的设计和制造至关重要。在这里，通过在拓扑绝缘子BI2SE3薄膜中使用自旋分辨的光发射光谱与p极光，我们报告了拓扑绝缘子薄膜在金属对绝缘体过渡的拓扑构型中的隧道依赖性演变。我们报告了超薄式dirac-cone极限中拓扑表面电子的系统结合能量和波形依赖性自旋极化。在薄绝缘膜中系统地实现的隧穿时，极化量显着降低，而在较厚的金属膜中，极化的幅度在较大的波形处饱和到散装极限。我们提出了一个理论模型，该模型捕获了量子隧穿和费米表面自旋极化之间的这种微妙的关系。我们的高分辨率基于自旋的光谱结果表明，在薄绝缘膜中可以将极化电流调节为零，从而为将来的自旋切换纳米电视构成基础。
Understanding the spin-texture behaviour of boundary modes in ultrathin topological insulator films is critically essential for the design and fabrication of functional nanodevices. Here, by using spin-resolved photoemission spectroscopy with p-polarized light in topological insulator Bi2Se3 thin films, we report tunnelling-dependent evolution of spin configuration in topological insulator thin films across the metal-to-insulator transition. We report a systematic binding energy-and wavevector-dependent spin polarization for the topological surface electrons in the ultrathin gapped-Dirac-cone limit. The polarization decreases significantly with enhanced tunnelling realized systematically in thin insulating films, whereas magnitude of the polarization saturates to the bulk limit faster at larger wavevectors in thicker metallic films. We present a theoretical model that captures this delicate relationship between quantum tunnelling and Fermi surface spin polarization. Our high-resolution spin-based spectroscopic results suggest that the polarization current can be tuned to zero in thin insulating films forming the basis for a future spin-switch nanodevice.