  Spin-dependent properties of single-layer graphene (SLG) have been studied by
non-local spin valve measurements at room temperature. Gate voltage dependence
shows that the non-local magnetoresistance (MR) is proportional to the
conductivity of the SLG, which is the predicted behavior for transparent
ferromagnetic/nonmagnetic contacts. While the electron and hole bands in SLG
are symmetric, gate voltage and bias dependence of the non-local MR reveal an
electron-hole asymmetry in which the non-local MR is roughly independent of
bias for electrons, but varies significantly with bias for holes.
