We calculate the spin transport of hydrogenated graphene using the Landauer-Büttiker formalism with a spin-dependent tight-binding Hamiltonian. Hydrogen adatoms are a common defect and they carry a finite magnetic moment, which makes it important to understand their influence on spin transport for graphene-based spin devices. Our tight-binding model accurately reproduces the density-functional theory band structure and atom-projected density of states. The advantages of using the Landauer-Büttiker formalism are that it simultaneously gives information on sheet resistance and localization length as well as spin relaxation length. Furthermore, the transport can be computed very efficiently using this method by employing the recursive Green's function technique. Here, we study hydrogen adatoms on graphene with randomly aligned magnetic moments, where interference effects are explicitly included. We show that a 5 ppm hydrogen defect density is sufficient to reduce the spin relaxation length to $2\mu \mathrm{m}$ and that the inverse spin relaxation length and sheet resistance scale nearly linearly with the impurity concentration. Moreover, the spin relaxation mechanism in hydrogenated graphene is Markovian only near the charge neutrality point or in the highly dilute impurity limit.

• Received 17 July 2015
• Revised 3 September 2015

DOI:https://doi.org/10.1103/PhysRevB.92.195408