Yan Yuan, Wang Li-Xian, Ke Xiaoxing, Van Tendeloo Gustaaf, Wu Xiao-Song, Yu Da-Peng, Liao Zhi-Min
1] State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, P.R. China [2].
1] EMAT (Electron Microscopy for Materials Science), University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium [2].
Sci Rep. 2014 Jan 22;4:3817. doi: 10.1038/srep03817.
Magnetotransport measurements of topological insulators are very important to reveal the exotic topological surface states for spintronic applications. However, the novel properties related to the surface Dirac fermions are usually accompanied by a large linear magnetoresistance under perpendicular magnetic field, which makes the identification of the surface states obscure. Here, we report prominent Shubnikov-de Haas (SdH) oscillations under an in-plane magnetic field, which are identified to originate from the surface states in the sidewalls of topological insulator Bi2Se3 nanoplates. Importantly, the SdH oscillations appear with a dramatically weakened magnetoresistance background, offering an easy path to probe the surface states directly when the coexistence of surface states and bulk conduction is inevitable. Moreover, under a perpendicular magnetic field, the oscillations in Hall conductivity have peak-to-valley amplitudes of 2 e(2)/h, giving confidence to achieve a quantum Hall effect in this system. A cross-section view of the nanoplate shows that the sidewall is (015) facet dominant and therefore forms a 58° angle with regard to the top/bottom surface instead of being perpendicular; this gives credit to the surface states' behavior as two-dimensional transport.
拓扑绝缘体的磁输运测量对于揭示用于自旋电子学应用的奇异拓扑表面态非常重要。然而，与表面狄拉克费米子相关的新奇特性通常伴随着垂直磁场下的大线性磁阻，这使得表面态的识别变得模糊。在此，我们报道了在面内磁场下显著的舒布尼科夫 - 德哈斯（SdH）振荡，这些振荡被确定源自拓扑绝缘体Bi2Se3纳米片侧壁中的表面态。重要的是，SdH振荡出现时磁阻背景显著减弱，当表面态和体传导不可避免地共存时，这为直接探测表面态提供了一条便捷途径。此外，在垂直磁场下，霍尔电导率的振荡具有2e(2)/h的峰谷幅度，这为在该系统中实现量子霍尔效应提供了信心。纳米片的横截面视图显示，侧壁以（015）面为主，因此相对于顶面/底面形成58°角而非垂直；这证实了表面态作为二维输运的行为。
