Quantum and classical magnetoresistance in ambipolar topological insulator transistors with gate-tunable bulk and surface conduction.
Quantum and classical magnetoresistance in ambipolar topological insulator transistors with gate-tunable bulk and surface conduction.
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具有栅极可调体传导和表面传导的双极拓扑绝缘体晶体管中的量子和经典磁阻
DOI：
10.1038/srep04859
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发表时间：
2014-05-07
影响因子：
4.6
通讯作者：
Chen YP
中科院分区：
文献类型：
--
作者：
Tian J;Chang C;Cao H;He K;Ma X;Xue Q;Chen YP
弱反局域化（WAL）和线性磁阻（LMR）是拓扑绝缘体（TIs）中两种最常见的磁阻（MR）现象，并且通常归因于狄拉克拓扑表面态（TSS）。然而，存在模糊性，因为这些现象也可能源于体态（在许多拓扑绝缘体中通常具有显著的导电性），并且甚至在非拓扑绝缘体材料中也可观察到。在此，我们展示了在SrTiO₃(111)上通过分子束外延生长的(Bi₀.₀₄Sb₀.₉₆)₂Te₃薄膜中的背栅双极性拓扑绝缘体场效应晶体管，其展现出大的载流子密度可调性（近2个数量级）以及体中的金属 - 绝缘体转变（允许关闭体导电）。将费米能级从体带调谐到拓扑表面态强烈增强了弱反局域化（将量子相干通道的数量从1个增加到峰值约为2个）和线性磁阻（将其斜率提高多达10倍）。表面态增强的线性磁阻伴随着强烈的非线性霍尔效应，这表明电荷不均匀性（以及相关的经典线性磁阻）具有重要作用，尽管现有的线性磁阻模型无法涵盖我们数据的所有方面。我们系统的栅极和温度相关的磁输运研究为两种磁阻现象的本质提供了更深入的见解，并揭示了拓扑绝缘体相关材料中体输运和拓扑表面态输运之间的差异。
Weak antilocalization (WAL) and linear magnetoresistance (LMR) are two most commonly observed magnetoresistance (MR) phenomena in topological insulators (TIs) and often attributed to the Dirac topological surface states (TSS). However, ambiguities exist because these phenomena could also come from bulk states (often carrying significant conduction in many TIs) and are observable even in non-TI materials. Here, we demonstrate back-gated ambipolar TI field-effect transistors in (Bi0.04Sb0.96)2Te3thin films grown by molecular beam epitaxy on SrTiO3(111), exhibiting a large carrier density tunability (by nearly 2 orders of magnitude) and a metal-insulator transition in the bulk (allowing switching off the bulk conduction). Tuning the Fermi level from bulk band to TSS strongly enhances both the WAL (increasing the number of quantum coherent channels from one to peak around two) and LMR (increasing its slope by up to 10 times). The SS-enhanced LMR is accompanied by a strongly nonlinear Hall effect, suggesting important roles of charge inhomogeneity (and a related classical LMR), although existing models of LMR cannot capture all aspects of our data. Our systematic gate and temperature dependent magnetotransport studies provide deeper insights into the nature of both MR phenomena and reveal differences between bulk and TSS transport in TI related materials.
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影响因子：
4
作者：
He, Hongtao;Li, Baikui;Wang, Jiannong
通讯作者：
Wang, Jiannong
影响因子：
4
作者：
Assaf, B. A.;Cardinal, T.;Heiman, D.
通讯作者：
Heiman, D.
影响因子：
2.1
作者：
Blake, P.;Yang, R.;Geim, A. K.
通讯作者：
Geim, A. K.
影响因子：
41.2
作者：
Hu, Jingshi;Rosenbaum, T. F.
通讯作者：
Rosenbaum, T. F.
影响因子：
8.6
作者：
Chen, J.;Qin, H. J.;Lu, L.
通讯作者：
Lu, L.