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

TL;DR

This paper models spin relaxation in bilayer graphene as caused by resonant scattering from magnetic impurities, explaining experimental observations and predicting a sharp decrease in relaxation rate at high carrier densities.

Contribution

It introduces a resonant scattering model for magnetic impurities in bilayer graphene that accounts for observed spin relaxation behavior and predicts new experimental features.

Findings

Resonant scattering by adatoms explains spin relaxation trends.

Narrow resonances occur at the charge neutrality point for dimer site impurities.

The model predicts a sharp decrease in relaxation rate at high carrier densities.

Abstract

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.