Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan.
1] Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan [2] PRESTO, Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-0075, Japan.
Nat Commun. 2015 Apr 14;6:6627. doi: 10.1038/ncomms7627.
The three-dimensional topological insulator is a novel state of matter characterized by two-dimensional metallic Dirac states on its surface. To verify the topological nature of the surface states, Bi-based chalcogenides such as Bi2Se3, Bi2Te3, Sb2Te3 and their combined/mixed compounds have been intensively studied. Here, we report the realization of the quantum Hall effect on the surface Dirac states in (Bi1-xSbx)2Te3 films. With electrostatic gate-tuning of the Fermi level in the bulk band gap under magnetic fields, the quantum Hall states with filling factor ±1 are resolved. Furthermore, the appearance of a quantum Hall plateau at filling factor zero reflects a pseudo-spin Hall insulator state when the Fermi level is tuned in between the energy levels of the non-degenerate top and bottom surface Dirac points. The observation of the quantum Hall effect in three-dimensional topological insulator films may pave a way toward topological insulator-based electronics.
三维拓扑绝缘体是一种新型物质态，其表面具有二维金属狄拉克态。为了验证表面态的拓扑性质，人们对基于 Bi 的硫属化物（如 Bi2Se3、Bi2Te3、Sb2Te3 及其组合/混合化合物）进行了深入研究。在这里，我们报告了在（Bi1-xSbx）2Te3 薄膜的表面狄拉克态上实现量子霍尔效应。通过在磁场下对体带隙中的费米能级进行静电门控调节，可以分辨出具有填充因子 ±1 的量子霍尔态。此外，当费米能级在非简并的顶部和底部表面狄拉克点能级之间调节时，填充因子为零处出现量子霍尔平台，反映出赝自旋霍尔绝缘体态。在三维拓扑绝缘体薄膜中观察到量子霍尔效应可能为基于拓扑绝缘体的电子学铺平道路。
