Zhu Qizhong, Tu Matisse Wei-Yuan, Tong Qingjun, Yao Wang
Department of Physics and Center of Theoretical and Computational Physics, University of Hong Kong, Hong Kong, China.
Sci Adv. 2019 Jan 18;5(1):eaau6120. doi: 10.1126/sciadv.aau6120. eCollection 2019 Jan.
Van der Waals heterostructures of two-dimensional (2D) materials provide a powerful approach toward engineering various quantum phases of matter. Examples include topological matter such as quantum spin Hall (QSH) insulator and correlated matter such as exciton superfluid. It can be of great interest to realize these vastly different quantum phases matter on a common platform; however, their distinct origins tend to restrict them to material systems of incompatible characters. Here, we show that heterobilayers of 2D valley semiconductors can be tuned through interlayer bias between an exciton superfluid, a quantum anomalous Hall insulator, and a QSH insulator. The tunability between these distinct phases results from the competition of Coulomb interaction with the interlayer quantum tunneling that has a chiral form in valley semiconductors. Our findings point to exciting opportunities for harnessing both protected topological edge channels and bulk superfluidity in an electrically configurable platform.
二维（2D）材料的范德华异质结构为构建各种量子物质相提供了一种强有力的方法。实例包括拓扑物质，如量子自旋霍尔（QSH）绝缘体，以及关联物质，如激子超流体。在一个共同平台上实现这些截然不同的量子物质相可能会非常有趣；然而，它们不同的起源往往将它们限制在具有不相容特性的材料体系中。在这里，我们表明二维谷半导体的异质双层可以通过激子超流体、量子反常霍尔绝缘体和QSH绝缘体之间的层间偏压进行调控。这些不同相之间的可调性源于库仑相互作用与层间量子隧穿的竞争，而层间量子隧穿在谷半导体中具有手性形式。我们的发现指出了在一个电可配置平台上利用受保护的拓扑边缘通道和体超流体的令人兴奋的机会。
