Nature Phys. (2013)

As a consequence of being made up of relatively light carbon atoms, the intrinsic spin–orbit coupling present in graphene is rather weak. This limits its potential for possible spintronic applications, because the spin–orbit interaction enables the generation and manipulation of spins solely by means of electric, rather than magnetic, fields. Jayakumar Balakrishnan et al. overcome this problem by adding small amounts of covalently bonded hydrogen atoms to the material, and show this induces an enhancement of the spin–orbit interaction by up to three orders of magnitude. Out-of-plane distortions to the sp2-hybridized planar carbon bonds have been predicted to enhance the spin–orbit coupling, but introducing these without significantly altering the metallic characteristics of graphene had been problematic. By hydrogenating the material a controlled conversion from sp2 to sp3 bonds is undergone, leading to a dramatic enhancement in the spin–orbit coupling. This also enabled Balakrishnan et al. to observe the spin Hall effect, which is essential for controlling spin currents, up to room temperature.