Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Nat Commun. 2011 Dec 20;2:596. doi: 10.1038/ncomms1602.
Topological insulators are characterized by a non-trivial band topology driven by the spin-orbit coupling. To fully explore the fundamental science and application of topological insulators, material realization is indispensable. Here we predict, based on tight-binding modelling and first-principles calculations, that bilayers of perovskite-type transition-metal oxides grown along the [111] crystallographic axis are potential candidates for two-dimensional topological insulators. The topological band structure of these materials can be fine-tuned by changing dopant ions, substrates and external gate voltages. We predict that LaAuO(3) bilayers have a topologically non-trivial energy gap of about 0.15 eV, which is sufficiently large to realize the quantum spin Hall effect at room temperature. Intriguing phenomena, such as fractional quantum Hall effect, associated with the nearly flat topologically non-trivial bands found in e(g) systems are also discussed.
拓扑绝缘体的特征在于由自旋轨道耦合驱动的非平凡能带拓扑结构。为了充分探索拓扑绝缘体的基础科学和应用，材料的实现是必不可少的。在这里，我们基于紧束缚模型和第一性原理计算预测，沿[111]晶轴生长的钙钛矿型过渡金属氧化物双层是二维拓扑绝缘体的潜在候选材料。通过改变掺杂离子、衬底和外部栅极电压，可以精细调整这些材料的拓扑带结构。我们预测 LaAuO(3)双层具有约 0.15 eV 的拓扑非平凡能隙，足以在室温下实现量子自旋霍尔效应。还讨论了与 e(g)系统中发现的近乎平坦的拓扑非平凡带相关的有趣现象，如分数量子霍尔效应。
