Spin transport in high quality suspended graphene devices
  We measure spin transport in high mobility suspended graphene (\mu ~ 10^5 cm^2/Vs), obtaining a (spin) diffusion coefficient of 0.1 m^2/s and giving a lower bound on the spin relaxation time (\tau_s ~ 150 ps) and spin relaxation length (\lambda_s=4.7 \mu m) for intrinsic graphene. We develop a theoretical model considering the different graphene regions of our devices that explains our experimental data. 
M. H. D. Guimar\~aes, A. Veligura, P. J. Zomer, T. Maassen, I. J.   Vera-Marun, N. Tombros, and B. J. van Wees
cond-mat.mes-hall