Fachbereich Physik, Universität Konstanz, 78457 Konstanz, Germany.
ACS Nano. 2012 Jan 24;6(1):151-8. doi: 10.1021/nn203169j. Epub 2012 Jan 3.
We use in situ scanning tunneling microscopy (STM) to investigate intercalation of the ferromagnetic 3d metals Ni and Fe underneath a graphene monolayer on Rh(111). Upon thermal annealing of graphene/Rh(111) with the deposited metal on top, we observe the formation of epitaxial monatomic nanoislands grown pseudomorphically on Rh(111) and covered by graphene. The size and shape of intercalated nanoislands is strongly influenced by the local spatial variation of the graphene-Rh bonding strength. In particular, the side length of the intercalated nanoislands shows maxima around discrete values imposed by the periodicity of the graphene moiré. Intercalation can be performed efficiently and without any visible damage of the graphene overlayer in the studied temperature range between 670 and 870 K. We identify the main intercalation path to be via diffusion through pre-existing lattice defects in graphene, accompanied by the second mechanism which is based on the material diffusion via metal-generated defects followed by the defect healing of the graphene lattice. We deem these graphene-capped and sharply confined ferromagnetic nanoislands interesting in the fields of spintronics and nanomagnetism.
我们使用原位扫描隧道显微镜（STM）研究了在 Rh(111) 上的单层石墨烯下，铁磁 3d 金属 Ni 和 Fe 的嵌入。在顶部沉积金属的石墨烯/Rh(111)进行热退火后，我们观察到在 Rh(111)上外延生长的单原子纳米岛的形成，这些纳米岛被石墨烯覆盖。嵌入纳米岛的大小和形状强烈受到石墨烯-Rh 键合强度的局部空间变化的影响。特别是，嵌入纳米岛的边长在由石墨烯莫尔图案的周期性决定的离散值周围表现出最大值。在 670 至 870 K 的研究温度范围内，嵌入可以有效地进行，而石墨烯覆盖层没有任何可见的损伤。我们确定主要的嵌入途径是通过在石墨烯中预先存在的晶格缺陷进行扩散，同时还存在第二种机制，该机制基于通过金属产生的缺陷进行材料扩散，然后是石墨烯晶格的缺陷愈合。我们认为这些石墨烯覆盖的、尖锐限制的铁磁纳米岛在自旋电子学和纳米磁学领域很有趣。
