Spin Relaxation Mechanism in Graphene: Resonant Scattering by Magnetic Impurities
Spin Relaxation Mechanism in Graphene: Resonant Scattering by Magnetic Impurities
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DOI：
10.1103/physrevlett.112.116602
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发表时间：
2014-03-18
影响因子：
8.6
通讯作者：
Fabian, Jaroslav
中科院分区：
文献类型：
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作者：
Kochan, Denis;Gmitra, Martin;Fabian, Jaroslav
我们提出石墨烯中观察到的小（100 ps）自旋弛豫时间是由于局部磁矩的共振散射。在共振处，磁矩表现为自旋热点：只要交换作用大于共振宽度，自旋翻转散射率与自旋守恒散射率一样大。由于电子-空穴水坑的存在，共振峰的涂抹得到了与实验的定量一致，约为1ppm的局部矩。虽然磁矩可以来自多种来源，但我们特别考虑氢原子，它们也是共振散射体。同样的机制也可以在存在强烈的局部自旋轨道相互作用的情况下工作，但这需要石墨烯上的重吸附原子或更大的轻吸附原子覆盖密度。为了使我们的机制更加透明，我们还引入了电子在局部磁矩和Rashba自旋轨道相互作用下的共振散射的玩具原子链模型。
We propose that the observed small (100 ps) spin relaxation time in graphene is due to resonant scattering by local magnetic moments. At resonances, magnetic moments behave as spin hot spots: the spin-flip scattering rates are as large as the spin-conserving ones, as long as the exchange interaction is greater than the resonance width. Smearing of the resonance peaks by the presence of electron-hole puddles gives quantitative agreement with experiment, for about 1 ppm of local moments. Although magnetic moments can come from a variety of sources, we specifically consider hydrogen adatoms, which are also resonant scatterers. The same mechanism would also work in the presence of a strong local spin-orbit interaction, but this would require heavy adatoms on graphene or a much greater coverage density of light adatoms. To make our mechanism more transparent, we also introduce toy atomic chain models for resonant scattering of electrons in the presence of a local magnetic moment and Rashba spin-orbit interaction.