Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Str. 15, D-12489 Berlin, Germany.
Nat Commun. 2012;3:1232. doi: 10.1038/ncomms2227.
Graphene in spintronics is predominantly considered for spin current leads of high performance due to weak intrinsic spin-orbit coupling of the graphene π electrons. Externally induced large spin-orbit coupling opens the possibility of using graphene in active elements of spintronic devices such as the Das-Datta spin field-effect transistor. Here we show that Au intercalation at the graphene-Ni interface creates a giant spin-orbit splitting (~100 meV) of the graphene Dirac cone up to the Fermi energy. Photoelectron spectroscopy reveals the hybridization with Au 5d states as the source for this giant splitting. An ab initio model of the system shows a Rashba-split spectrum around the Dirac point of graphene. A sharp graphene-Au interface at the equilibrium distance accounts for only ~10 meV spin-orbit splitting and enhancement is due to the Au atoms in the hollow position that get closer to graphene and do not break the sublattice symmetry.
在自旋电子学中，由于石墨烯 π 电子的本征自旋轨道耦合较弱，因此主要考虑将其用于高性能的自旋电流引线。外部诱导的大自旋轨道耦合为使用石墨烯作为自旋电子器件的有源元件（如 Das-Datta 自旋场效应晶体管）开辟了可能性。在这里，我们表明，在石墨烯-Ni 界面处的 Au 插层会在石墨烯狄拉克锥中产生巨大的自旋轨道分裂（100 meV），直至费米能。光电子能谱揭示了与 Au 5d 态的杂化是这种巨大分裂的来源。该系统的第一性原理模型显示了在石墨烯狄拉克点周围的 Rashba 分裂谱。在平衡距离处，尖锐的石墨烯-Au 界面仅会导致10 meV 的自旋轨道分裂，而增强则是由于处于空心位置的 Au 原子更接近石墨烯，并且不会破坏亚晶格对称性。
