论文标题
单个原子杂质诱导的石墨烯中断裂对称态的纳米级探测
Nanoscale Probing of Broken-Symmetry States in Graphene Induced by Individual Atomic Impurities
论文作者
论文摘要
系统的固有对称性导致其能量光谱的多个变性。引入个别的原子质杂质可以在本地打破这些对称性，这有望提高杂质周围的自由度。尽管我们对固体的基本特性的理解至关重要，但迄今为止，由个别原子杂质引起的破碎对称状态已经避免了观察。在这里，我们报告了由两种类型的单个原子杂质诱导的石墨烯中断裂对称态的纳米级探测，即分离的氮掺杂剂和分离的氢原子在石墨烯上化学化。我们的实验表明，两种类型的原子杂质都可以在局部打破石墨烯的sublattice对称性，并产生山谷偏振状态，从而扩展杂质周围的几种纳米。对于在石墨烯上的分离的氢原子化学吸附剂，增强的自旋轨道耦合是由于氢化学吸附而引起的石墨烯的SP3失真，进一步提高了自旋退化，从而在氢原子周围大约1 nm内实现了完全自旋和山谷极化状态。我们的结果铺平了通过各种原子杂质在纳米级控制各种破碎对称状态的方法。
Inherent symmetries of a system lead to multiple degeneracies of its energy spectra. Introducing individual atomic impurities can locally break these symmetries, which is expected to lift the degenerate degrees of freedom around the impurities. Although central to our understanding of the fundamental properties of solids, the broken-symmetry states induced by individual atomic impurities have so far eluded observation. Here, we report nanoscale probing of the broken-symmetry states in graphene induced by two types of individual atomic impurities, i.e., isolated nitrogen dopants and isolated hydrogen atoms chemisorbed on graphene. Our experiments demonstrate that both types of atomic impurities can locally break sublattice symmetry of graphene and generate valley-polarized states, which extends several nanometers around the impurities. For the isolated hydrogen atom chemisorbed on graphene, the enhanced spin-orbit coupling, which arises from the sp3 distortion of graphene due to the hydrogen chemisorption, further lifts the spin degeneracy, resulting in a fully spin and valley polarized states within about 1 nm around the hydrogen atom. Our result paves the way to control various broken-symmetry states at the nanoscale by various atomic impurities.
