Gate tunable relativistic mass and Berry's phase in topological insulator nanoribbon field effect devices.
Gate tunable relativistic mass and Berry's phase in topological insulator nanoribbon field effect devices.
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DOI：
10.1038/srep08452
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发表时间：
2015-02-13
影响因子：
4.6
通讯作者：
Chen YP
中科院分区：
文献类型：
--
作者：
Jauregui LA;Pettes MT;Rokhinson LP;Shi L;Chen YP
由于自旋螺旋无质量狄拉克费米子表面态的输运对于在拓扑绝缘体中实现从量子反常霍尔效应到马约拉纳费米子等各种新的物理现象至关重要。然而，拓扑表面态最重要的标志之一——狄拉克线性能带色散，在输运测量中一直难以直接揭示。在此，我们报道了在高κ钛酸锶（SrTiO₃）衬底上的Bi₂Te₃纳米带双极性场效应器件的实验，在该实验中我们实现了栅极调控的体金属 - 绝缘体转变以及具有显著表面态传导的拓扑输运机制。在这种机制下，我们通过舒布尼科夫 - 德哈斯振荡中的π贝里相位以及与费米动量成正比的有效质量，报道了栅极可调狄拉克费米子的两个明确的输运证据，这表明了能量 - 动量呈线性色散。我们还测量了在电荷中性点附近具有2个相干传导通道（表明2个解耦表面）的栅极可调弱反局域化（WAL），以及当费米能接近体导带时向弱局域化的转变（表明贝里相位的崩溃）。栅极可调狄拉克费米子拓扑表面态为各种拓扑电子器件铺平了道路。
Transport due to spin-helical massless Dirac fermion surface state is of paramount importance to realize various new physical phenomena in topological insulators, ranging from quantum anomalous Hall effect to Majorana fermions. However, one of the most important hallmarks of topological surface states, the Dirac linear band dispersion, has been difficult to reveal directly in transport measurements. Here we report experiments on Bi2Te3 nanoribbon ambipolar field effect devices on high-κ SrTiO3 substrates, where we achieve a gate-tuned bulk metal-insulator transition and the topological transport regime with substantial surface state conduction. In this regime, we report two unambiguous transport evidences for gate-tunable Dirac fermions through π Berry's phase in Shubnikov-de Haas oscillations and effective mass proportional to the Fermi momentum, indicating linear energy-momentum dispersion. We also measure a gate-tunable weak anti-localization (WAL) with 2 coherent conduction channels (indicating 2 decoupled surfaces) near the charge neutrality point, and a transition to weak localization (indicating a collapse of the Berry's phase) when the Fermi energy approaches the bulk conduction band. The gate-tunable Dirac fermion topological surface states pave the way towards a variety of topological electronic devices.