On-surface synthesis of graphene nanoribbons with zigzag edge topology
On-surface synthesis of graphene nanoribbons with zigzag edge topology
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DOI：
10.1038/nature17151
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发表时间：
2016-03-24
期刊：
影响因子：
64.8
通讯作者：
Fasel, Roman
中科院分区：
文献类型：
--
作者：
Ruffieux, Pascal;Wang, Shiyong;Fasel, Roman
基于石墨烯的纳米结构表现出在延伸石墨烯中不存在的电子性质。例如，碳纳米管和扶手椅型石墨烯纳米带中的量子限制导致与其结构边界条件直接相关的大量电子带隙的开放（1，2）。具有锯齿形边缘的纳米结构预计将拥有自旋极化的电子边缘状态，因此可以作为石墨烯基自旋电子学的关键元素（3）。锯齿形石墨烯纳米带（ZGNR）的边缘状态被预测为沿着边缘铁磁耦合并且在边缘之间反铁磁耦合（4），但是由于当前自上而下方法的有限精度，尚未实现对锯齿形边缘拓扑（包括ZGNR）的自旋极化边缘状态的直接观察（5-10）。在这里，我们描述了自下而上的合成ZGNRs通过表面辅助聚合和环化脱氢的专门设计的前体单体，以产生原子精确的锯齿形边缘。利用扫描隧道光谱，我们表明存在的边缘局域态与大的能量分裂。我们预计ZGNR的可用性将能够表征其预测的自旋相关特性，例如自旋限制（11）和过滤（12，13），并最终将自旋自由度添加到石墨烯基电路中。
Graphene-based nanostructures exhibit electronic properties that are not present in extended graphene. For example, quantum confinement in carbon nanotubes and armchair graphene nanoribbons leads to the opening of substantial electronic bandgaps that are directly linked to their structural boundary conditions(1,2). Nanostructures with zigzag edges are expected to host spin-polarized electronic edge states and can thus serve as key elements for graphene-based spintronics(3). The edge states of zigzag graphene nanoribbons (ZGNRs) are predicted to couple ferromagnetically along the edge and antiferromagnetically between the edges(4), but direct observation of spin-polarized edge states for zigzag edge topologies-including ZGNRs-has not yet been achieved owing to the limited precision of current top-down approaches(5-10). Here we describe the bottom-up synthesis of ZGNRs through surface-assisted polymerization and cyclodehydrogenation of specifically designed precursor monomers to yield atomically precise zigzag edges. Using scanning tunnelling spectroscopy we show the existence of edge-localized states with large energy splittings. We expect that the availability of ZGNRs will enable the characterization of their predicted spin-related properties, such as spin confinement(11) and filtering(12,13), and will ultimately add the spin degree of freedom to graphene-based circuitry.