Spin currents which allow for a dissipationless transport of information can
be generated by electric fields in semiconductor heterostructures in the
presence of a Rashba-type spin-orbit coupling. The largest Rashba effects occur
for electronic surface states of metals but these cannot exist but under
ultrahigh vacuum conditions. Here, we reveal a giant Rashba effect ({\alpha}_R
~ 1.5E-10 eVm) on a surface state of Ir(111). We demonstrate that its spin
splitting and spin polarization remain unaffected when Ir is covered with
graphene. The graphene protection is, in turn, sufficient for the spin-split
surface state to survive in ambient atmosphere. We discuss this result along
with evidences for a topological protection of the surface state.Comment: includes supplementary informatio
