Rader O, Varykhalov A, Sánchez-Barriga J, Marchenko D, Rybkin A, Shikin A M
Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.
Phys Rev Lett. 2009 Feb 6;102(5):057602. doi: 10.1103/PhysRevLett.102.057602.
Graphene is considered a candidate material for spintronics. Recently, graphene grown on Ni(111) has been reported to show a Rashba effect which depends on the magnetization. By spin- and angle-resolved photoelectron spectroscopy, we investigate the preconditions for such an effect for graphene on Ni as well as on Co which has a approximately 3x larger 3d magnetic moment: (i) spin polarization or (ii) exchange splitting of graphene pi states in normal emission geometry, and (iii) Rashba-type spin-orbit splitting off normal. As none of these are found to be of considerable size, the reported effect is neither Rashba-type, nor due to the spin-orbit coupling, nor involving the electron spin.
石墨烯被认为是自旋电子学的候选材料。最近，有报道称在Ni(111)上生长的石墨烯表现出一种依赖于磁化强度的Rashba效应。通过自旋和角分辨光电子能谱，我们研究了石墨烯在Ni以及具有大约大三倍3d磁矩的Co上产生这种效应的前提条件：(i) 自旋极化，或 (ii) 正常发射几何结构中石墨烯π态的交换劈裂，以及 (iii) 垂直于法线方向的Rashba型自旋轨道劈裂。由于发现这些条件都没有达到可观的程度，所以报道的效应既不是Rashba型的，也不是由于自旋轨道耦合，也不涉及电子自旋。
