State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, People's Republic of China.
J Phys Condens Matter. 2011 Jun 8;23(22):225502. doi: 10.1088/0953-8984/23/22/225502. Epub 2011 May 17.
Substrate-induced spin-orbit splitting in graphene on Ni, Au and Ag(111) is examined on the basis of density-functional theory. The Rashba splitting of π bands along the ΓM direction of the graphene surface Brillouin zone in graphene on Ni(111) is found to be very small (a few millielectronvolts), consistent with the experimental report of Rader et al. Instead, very strong Rashba splitting (near 100 meV) can be obtained for graphene with a certain stretch distortion on a Au substrate. It can be ascribed to the effective match in energy between the C 2p and Au 5d bands, obtained from the analysis of densities of states. The net charge transfer between the graphene and the substrates just affects the spin-orbit effect indirectly. The small spin-orbit splitting induced by the Ag substrates indicates that heavy metals do not always produce large SO splitting. Our findings provide important insights that are useful for understanding the metal-induced Rashba effect in graphene.
基于密度泛函理论，研究了 Ni、Au 和 Ag(111) 上石墨烯的衬底诱导的自旋轨道劈裂。发现 Ni(111) 上石墨烯中 ΓM 方向的π带的 Rashba 劈裂非常小（几毫电子伏特），与 Rader 等人的实验报告一致。相反，在 Au 衬底上具有一定拉伸变形的石墨烯可以获得很强的 Rashba 劈裂（近 100 毫电子伏特）。这可以归因于从态密度分析中获得的 C 2p 和 Au 5d 能带之间的能量有效匹配。石墨烯与衬底之间的净电荷转移仅间接地影响自旋轨道效应。Ag 衬底引起的小自旋轨道劈裂表明，重金属并不总是产生大的 SO 劈裂。我们的发现为理解石墨烯中的金属诱导 Rashba 效应提供了重要的见解。
