Emergence of Decoupled Surface Transport Channels in Bulk Insulating Bi2Se3 Thin Films
Emergence of Decoupled Surface Transport Channels in Bulk Insulating Bi2Se3 Thin Films
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DOI：
10.1103/physrevlett.113.026801
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发表时间：
2014-07-07
影响因子：
8.6
通讯作者：
Oh, Seongshik
中科院分区：
文献类型：
--
作者：
Brahlek, Matthew;Koirala, Nikesh;Oh, Seongshik
在理想拓扑绝缘体（TI）膜中，体状态（其被认为是绝缘的）不应在两个金属表面之间提供任何电耦合。然而，现有的TI膜的运输研究表明，在相对的表面上的拓扑状态彼此电连接的厚度远远大于直接耦合限制的表面波功能重叠。在这里，我们表明，作为导电体通道被抑制，寄生耦合效应减小，和解耦的表面通道出现理想的TI预期。在具有完全抑制的体状态的Bi2Se3薄膜中，在类似于10 QL以下直接耦合的两个表面随着厚度的增加而逐渐隔离，并且在超过类似于20 QL时完全解耦。在这样的平台上，现在可以实现其功能依赖于访问各个表面层而没有任何有害耦合效应的传输设备。
In ideal topological insulator (TI) films the bulk state, which is supposed to be insulating, should not provide any electric coupling between the two metallic surfaces. However, transport studies on existing TI films show that the topological states on opposite surfaces are electrically tied to each other at thicknesses far greater than the direct coupling limit where the surface wave functions overlap. Here, we show that as the conducting bulk channels are suppressed, the parasitic coupling effect diminishes, and the decoupled surface channels emerge as expected for ideal TIs. In Bi2Se3 thin films with fully suppressed bulk states, the two surfaces, which are directly coupled below similar to 10 QL, become gradually isolated with increasing thickness and are completely decoupled beyond similar to 20 QL. On such a platform, it is now feasible to implement transport devices whose functionality relies on accessing the individual surface layers without any deleterious coupling effects.