Resonant scattering by magnetic impurities as a model for spin relaxation in bilayer graphene

摘要

We propose that the observed spin-relaxation in bilayer graphene is due toresonant scattering by magnetic impurities. We analyze a resonant scatteringmodel due to adatoms on both dimer and non-dimer sites, finding that only theformer give narrow resonances at the charge neutrality point. Opposite tosingle-layer graphene, the measured spin-relaxation rate in graphene bilayerincreases with carrier density. Although it has been commonly argued that adifferent mechanism must be at play for the two structures, our model explainsthis behavior rather naturally in terms of different broadening scales for thesame underlying resonant processes. Not only our results---using robust andfirst-principles inspired parameters---agree with experiment, they also predictan experimentally testable sharp decrease of the spin-relaxation rate at highcarrier densities.