Crossover of the three-dimensional topological insulator Bi2Se3 to the two-dimensional limit
Crossover of the three-dimensional topological insulator Bi2Se3 to the two-dimensional limit
复制标题
三维拓扑绝缘体Bi2Se3跨越到二维极限
DOI：
10.1038/nphys1689
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发表时间：
2010-08-01
期刊：
影响因子：
19.6
通讯作者：
Xue, Qi-Kun
中科院分区：
文献类型：
--
作者：
Zhang, Yi;He, Ke;Xue, Qi-Kun
拓扑绝缘体（1-9）是量子物质的一种新状态，其特征是体中有有限的能隙，而沿边界流动的无隙模式对无序散射具有鲁棒性。表面态的拓扑保护可以用于低功耗电子（10）和容错量子计算（11,12）。对于三维拓扑绝缘体的薄板，来自相对表面的边界模式可以通过量子隧穿耦合，从而打开一个小的、与厚度相关的间隙（13-15）。本文报道了用分子束外延生长的不同厚度Bi2Se3薄膜的角分辨光谱学结果。当厚度低于六层五层时，能隙开口清晰可见。由于衬底诱导的两个表面之间的电位差，间隙表面状态也表现出相当大的rashba型自旋轨道分裂。可调谐的间隙和自旋轨道耦合使这些拓扑薄膜成为电子和自旋电子器件应用的理想选择。
A topological insulator(1-9) is a new state of quantum matter that is characterized by a finite energy gap in the bulk and gapless modes flowing along the boundaries that are robust against disorder scattering. The topological protection of the surface state could be useful for both low-power electronics(10) and error-tolerant quantum computing(11,12). For a thin slab of three-dimensional topological insulator, the boundary modes from the opposite surfaces may be coupled by quantum tunnelling, so that a small, thickness-dependent gap is opened up(13-15). Here we report such results from angle-resolved photoemission spectroscopy on Bi2Se3 films of various thicknesses grown by molecular beam epitaxy. The energy gap opening is clearly seen when the thickness is below six quintuple layers. The gapped surface states also exhibit sizeable Rashba-type spin-orbit splitting because of the substrate-induced potential difference between the two surfaces. The tunable gap and the spin-orbit coupling make these topological thin films ideal for electronic and spintronic device applications.