Interdisciplinary School of Green Energy and Low Dimensional Carbon Materials Center, Ulsan 689-798, Korea.
Sci Rep. 2013 Nov 20;3:3276. doi: 10.1038/srep03276.
The conversion of multilayer graphenes into sp(3)-bonded carbon films on metal surfaces (through hydrogenation or fluorination of the outer surface of the top graphene layer) is indicated through first-principles computations. The main driving force for this conversion is the hybridization between sp(3) orbitals and metal surface dz(2) orbitals. The induced electronic gap states and spin moments in the carbon layers are confined in a region within 0.5 nm of the metal surface. Whether the conversion occurs depend on the fraction of hydrogenated (fluorinated) C atoms at the outer surface and on the number of stacked graphene layers. In the analysis of the Eliashberg spectral functions for the sp(3) carbon films on a metal surface that is diamagnetic, the strong covalent metal-sp(3) carbon bonds induce soft phonon modes that predominantly contribute to large electron-phonon couplings, suggesting the possibility of phonon-mediated superconductivity. Our computational results suggest a route to experimental realization of large-area ultrathin sp(3)-bonded carbon films on metal surfaces.
通过第一性原理计算，表明多层石墨烯在金属表面上可以转化为 sp(3)键合的碳膜（通过顶层石墨烯层的外表面的氢化或氟化）。这种转化的主要驱动力是 sp(3)轨道和金属表面 dz(2)轨道之间的杂化。在碳层中诱导的电子带隙态和自旋矩被限制在距金属表面 0.5nm 的范围内。这种转化是否发生取决于外表面氢化（氟化）C 原子的分数和堆叠的石墨烯层数。在分析具有抗磁性的金属表面上的 sp(3)碳膜的 Eliashberg 谱函数时，强共价金属-sp(3)碳键诱导软声子模式，主要贡献于大的电子-声子耦合，这表明了声子介导超导的可能性。我们的计算结果为在金属表面上实现大面积超薄 sp(3)键合碳膜的实验提供了一条途径。
