Physics of Interfaces and Nanomaterials, MESA+ Institute, University of Twente, Drienerlolaan 5, 7522 NB, Enschede, Netherlands.
Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing 100081, China.
Phys Rev Lett. 2023 May 12;130(19):196401. doi: 10.1103/PhysRevLett.130.196401.
We present the first experimental evidence of a topological phase transition in a monoelemental quantum spin Hall insulator. Particularly, we show that low-buckled epitaxial germanene is a quantum spin Hall insulator with a large bulk gap and robust metallic edges. Applying a critical perpendicular electric field closes the topological gap and makes germanene a Dirac semimetal. Increasing the electric field further results in the opening of a trivial gap and disappearance of the metallic edge states. This electric field-induced switching of the topological state and the sizable gap make germanene suitable for room-temperature topological field-effect transistors, which could revolutionize low-energy electronics.
我们首次在单元素量子自旋霍尔绝缘体中观察到拓扑相变的实验证据。具体而言，我们证明了低弯曲外延锗烯是一种具有大带隙和稳定金属边缘的量子自旋霍尔绝缘体。施加临界垂直电场可以关闭拓扑带隙，使锗烯成为狄拉克半金属。进一步增加电场会导致平凡带隙的打开和金属边缘态的消失。这种电场诱导的拓扑态转变和可观的带隙使得锗烯适用于室温拓扑场效应晶体管，这可能会彻底改变低能耗电子学。
