We propose that the observed spin-relaxation in bilayer graphene is due to
resonant scattering by magnetic impurities. We analyze a resonant scattering
model due to adatoms on both dimer and non-dimer sites, finding that only the
former give narrow resonances at the charge neutrality point. Opposite to
single-layer graphene, the measured spin-relaxation rate in graphene bilayer
increases with carrier density. Although it has been commonly argued that a
different mechanism must be at play for the two structures, our model explains
this behavior rather naturally in terms of different broadening scales for the
same underlying resonant processes. Not only our results---using robust and
first-principles inspired parameters---agree with experiment, they also predict
an experimentally testable sharp decrease of the spin-relaxation rate at high
carrier densities.Comment: 6 pages, 3 figures + 2 pages Suppl. Materia
