  Spin accumulation and spin precession in single-layer graphene are studied by
non-local spin valve measurements at room temperature. The dependence of the
non-local magnetoresistance on electrode spacing is investigated and the
results indicate a spin diffusion length of ~1.6 microns and a spin
injection/detection efficiency of 0.013. Electrical detection of the spin
precession confirms that the non-local signal originates from spin injection
and transport. Fitting of the Hanle spin precession data yields a spin
relaxation time of ~84 ps and a spin diffusion length of ~1.5 microns, which is
consistent with the value obtained through the spacing dependence.
