Carbon-based nanomaterials are promising for spintronic applications because their weak spin-orbit (SO) coupling and hyperfine interaction in carbon atoms entail exceptionally long spin diffusion lengths (~100µm) in carbon nanotubes and graphene. The exceptional electronic and transport features of carbon nanomaterials could be exploited to build multifunctional spintronic devices. However, a large spin diffusion length comes at the price of small SO coupling, which limits the possibility of manipulating electrons via an external applied field.