Nanoscale strain engineering of giant pseudo-magnetic fields, valley polarization, and topological channels in graphene
Nanoscale strain engineering of giant pseudo-magnetic fields, valley polarization, and topological channels in graphene
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DOI：
10.1126/sciadv.aat9488
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发表时间：
2020-05-01
期刊：
影响因子：
13.6
通讯作者：
Yeh, N-C
中科院分区：
文献类型：
--
作者：
Hsu, C-C;Teague, M. L.;Yeh, N-C
石墨烯中与两个不相等的谷相关的非平凡贝里相的存在为研究谷投影拓扑态提供了有趣的机会。此类研究的例子包括观察单层石墨烯中的异常量子霍尔效应，通过扫描隧道显微镜组装的“分子石墨烯”中的拓扑零模式的演示，以及在石墨烯超晶格或双层石墨烯畴壁中检测拓扑谷输运。然而，上述所有实验都涉及不可扩展的方法，无论是机械剥离薄片还是原子对原子的结构。在这里，我们报告了一种在室温下通过纳米尺度应变工程来操纵单层石墨烯拓扑状态的方法。通过将无应变单层石墨烯放置在体系结构纳米结构上以诱导全局反转对称性破缺，我们展示了巨大伪磁场（高达类似于800 T），谷极化和周期性一维拓扑通道的发展，以保护手性模式在应变石墨烯中的传播，从而为可扩展的石墨烯基谷电子学铺平了道路。
The existence of nontrivial Berry phases associated with two inequivalent valleys in graphene provides interesting opportunities for investigating the valley-projected topological states. Examples of such studies include observation of anomalous quantum Hall effect in monolayer graphene, demonstration of topological zero modes in "molecular graphene" assembled by scanning tunneling microscopy, and detection of topological valley transport either in graphene superlattices or at bilayer graphene domain walls. However, all aforementioned experiments involved nonscalable approaches of either mechanically exfoliated flakes or atom-by-atom constructions. Here, we report an approach to manipulating the topological states in monolayer graphene via nanoscale strain engineering at room temperature. By placing strain-free monolayer graphene on architected nanostructures to induce global inversion symmetry breaking, we demonstrate the development of giant pseudo-magnetic fields (up to similar to 800 T), valley polarization, and periodic one-dimensional topological channels for protected propagation of chiral modes in strained graphene, thus paving a pathway toward scalable graphene-based valleytronics.