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 $\sim 3\times$ 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.

• Received 19 October 2008

DOI:https://doi.org/10.1103/PhysRevLett.102.057602