Nanotech@surfaces Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland.
NCCR MARVEL, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland.
Nat Commun. 2016 May 16;7:11507. doi: 10.1038/ncomms11507.
Zigzag edges of graphene nanostructures host localized electronic states that are predicted to be spin-polarized. However, these edge states are highly susceptible to edge roughness and interaction with a supporting substrate, complicating the study of their intrinsic electronic and magnetic structure. Here, we focus on atomically precise graphene nanoribbons whose two short zigzag edges host exactly one localized electron each. Using the tip of a scanning tunnelling microscope, the graphene nanoribbons are transferred from the metallic growth substrate onto insulating islands of NaCl in order to decouple their electronic structure from the metal. The absence of charge transfer and hybridization with the substrate is confirmed by scanning tunnelling spectroscopy, which reveals a pair of occupied/unoccupied edge states. Their large energy splitting of 1.9 eV is in accordance with ab initio many-body perturbation theory calculations and reflects the dominant role of electron-electron interactions in these localized states.
石墨烯纳米结构的锯齿形边缘具有局域电子态，这些局域电子态被预测为具有自旋极化。然而，这些边缘态对边缘粗糙度和与支撑衬底的相互作用非常敏感，这使得研究其本征电子和磁结构变得复杂。在这里，我们关注的是原子精度的石墨烯纳米带，其两条短的锯齿形边缘各有一个局域电子。使用扫描隧道显微镜的尖端，将石墨烯纳米带从金属生长衬底转移到 NaCl 的绝缘岛上，以将其电子结构与金属分离。通过扫描隧道光谱法证实了没有电荷转移和与衬底的杂化，该光谱法揭示了一对占据/未占据的边缘态。它们的大能量分裂为 1.9 eV，与从头算多体微扰理论计算相符，反映了电子-电子相互作用在这些局域态中的主导作用。
