Tuning the Chern number in quantum anomalous Hall insulators
Tuning the Chern number in quantum anomalous Hall insulators
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DOI：
10.1038/s41586-020-3020-3
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发表时间：
2020-12
期刊：
影响因子：
64.8
通讯作者：
Yi-Fan Zhao;Ruoxi Zhang;Ruobing Mei;Ling Zhou;H. Yi;Ya-Qi Zhang;Jiabin Yu;Run Xiao;Ke Wan
中科院分区：
文献类型：
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作者：
Yi-Fan Zhao;Ruoxi Zhang;Ruobing Mei;Ling Zhou;H. Yi;Ya-Qi Zhang;Jiabin Yu;Run Xiao;Ke Wan
量子反常霍尔（QAH）态是一种二维拓扑绝缘态，其量子化霍尔电阻为h/(Ce2)，零磁场下纵向电阻为零（其中普朗克常数，e为基本电荷，陈数C为整数）。 QAH 效应已在磁性拓扑绝缘体 、 、 、 、 、 – 和魔角扭曲双层石墨烯中实现。然而，迄今为止，零磁场下的 QAH 效应仅在 C= 1 时实现。在这里，我们在由交替磁性和未掺杂拓扑绝缘体层组成的多层结构中实现了具有可调谐陈数（高达 C= 5）的良好量子化 QAH 效应，并使用分子束外延制造。这些 QAH 绝缘体的陈数由多层结构中未掺杂拓扑绝缘体层的数量决定。此外，我们证明给定多层结构的陈数可以通过改变磁性拓扑绝缘体层中的磁性掺杂浓度或内部磁性拓扑绝缘体层的厚度来调节。我们开发了一个理论模型来解释我们的实验观察结果，并建立了具有高可调陈数的 QAH 绝缘体的相图。这种绝缘体的实现促进了无耗散手性边缘电流在节能电子器件中的应用，并为开发多通道量子计算和更高容量的手性电路互连开辟了机会。
A quantum anomalous Hall (QAH) state is a two-dimensional topological insulating state that has a quantized Hall resistance ofh/(Ce2) and vanishing longitudinal resistance under zero magnetic field (wherehis the Planck constant,eis the elementary charge, and the Chern numberCis an integer),. The QAH effect has been realized in magnetic topological insulators, , , , , –and magic-angle twisted bilayer graphene,. However, the QAH effect at zero magnetic field has so far been realized only forC= 1. Here we realize a well quantized QAH effect with tunable Chern number (up toC= 5) in multilayer structures consisting of alternating magnetic and undoped topological insulator layers, fabricated using molecular beam epitaxy. The Chern number of these QAH insulators is determined by the number of undoped topological insulator layers in the multilayer structure. Moreover, we demonstrate that the Chern number of a given multilayer structure can be tuned by varying either the magnetic doping concentration in the magnetic topological insulator layers or the thickness of the interior magnetic topological insulator layer. We develop a theoretical model to explain our experimental observations and establish phase diagrams for QAH insulators with high, tunable Chern number. The realization of such insulators facilitates the application of dissipationless chiral edge currents in energy-efficient electronic devices, and opens up opportunities for developing multi-channel quantum computing and higher-capacity chiral circuit interconnects.