Competing Weak Localization and Weak Antilocalization in Ultrathin Topological Insulators
Competing Weak Localization and Weak Antilocalization in Ultrathin Topological Insulators
复制标题
超薄拓扑绝缘体中弱局域化和弱反局域化的竞争
DOI：
10.1021/nl303424n
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发表时间：
2013-01-01
期刊：
影响因子：
10.8
通讯作者：
Wang, Kang L.
中科院分区：
文献类型：
--
作者：
Lang, Murong;He, Liang;Wang, Kang L.
通过传输和扫描隧道光谱测量，我们证明了（Bi0.57Sb0.43）(2)Te-3拓扑绝缘体（TI）薄膜在六层以下的表面间隙打开的证据。通过栅极电压控制有效调节费米能级，我们揭示了非磁性超薄膜在低磁场下弱局域化和弱反局域化之间的显著竞争，这可能是由于净贝里相的变化。此外，当费米能级被扫入超薄样品的表面间隙时，在更高的磁场下显示出整体的统一行为，这与在较厚的薄膜中获得的纯WAL信号相反。我们的研究结果显示了一种奇特的现象，表征了TI表面状态的间隙，并指出了未来实现量子自旋霍尔效应和基于无耗散TI的应用。
We demonstrate evidence of a surface gap opening in topological insulator (TI) thin films of (Bi0.57Sb0.43)(2)Te-3 below six quintuple layers through transport and scanning tunneling spectroscopy measurements. By effective tuning the Fermi level via gate-voltage control, we unveil a striking competition between weak localization and weak antilocalization at low magnetic fields in nonmagnetic ultrathin films, possibly owing to the change of the net Berry phase. Furthermore, when the Fermi level is swept into the surface gap of ultrathin samples, the overall unitary behaviors are revealed at higher magnetic fields, which are in contrast to the pure WAL signals obtained in thicker films. Our findings show an exotic phenomenon characterizing the gapped TI surface states and point to the future realization of quantum spin Hall effect and dissipationless TI-based applications.