Linear scaling between momentum and spin scattering in graphene

Spin transport in graphene carries the potential of a long spin-diffusion length at room temperature. However, extrinsic relaxation processes limit the current experimental values to 1-2 mu m. We present Hanle spin precession measurements in gated lateral spin valve devices in the low to high (up to 10(13) cm(-2)) carrier density range of graphene. A linear scaling between the spin-diffusion length and the diffusion coefficient is observed. We measure nearly identical spin- and charge diffusion coefficients indicating that electron-electron interactions are relatively weak and transport is limited by impurity potential scattering. When extrapolated to the maximum carrier mobilities of 2x10(5) cm(2)/Vs, our results predict that a considerable increase in the spin-diffusion length should be possible.