Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany.
Phys Rev Lett. 2015 Nov 6;115(19):196601. doi: 10.1103/PhysRevLett.115.196601. Epub 2015 Nov 4.
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 nondimer 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 the 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 do 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.
我们提出，在双层石墨烯中观察到的自旋弛豫是由于共振散射磁性杂质引起的。我们分析了一个由于二聚体和非二聚体位置上的 adatoms 引起的共振散射模型，发现只有前者在电荷中性点处给出窄共振。与单层石墨烯相反，在双层石墨烯中测量到的自旋弛豫率随载流子密度增加而增加。尽管人们普遍认为对于这两种结构，必须采用不同的机制，但我们的模型根据相同的基本共振过程的不同展宽尺度，相当自然地解释了这种行为。我们的结果不仅使用了稳健且受第一性原理启发的参数，与实验相符，还预测了在高载流子密度下自旋弛豫率的可实验验证的急剧下降。
