Department of Physics and Astronomy, University of California, Riverside, California 92521, USA.
Phys Rev Lett. 2011 Jul 22;107(4):047207. doi: 10.1103/PhysRevLett.107.047207. Epub 2011 Jul 21.
We investigate spin relaxation in graphene spin valves and observe strongly contrasting behavior for single-layer graphene (SLG) and bilayer graphene (BLG). In SLG, the spin lifetime (τ(s)) varies linearly with the momentum scattering time (τ(p)) as carrier concentration is varied, indicating the dominance of Elliot-Yafet (EY) spin relaxation at low temperatures. In BLG, τ(s) and τ(p) exhibit an inverse dependence, which indicates the dominance of Dyakonov-Perel spin relaxation at low temperatures. The different behavior is due to enhanced screening and/or reduced surface sensitivity of BLG, which greatly reduces the impurity-induced EY spin relaxation.
我们研究了石墨烯自旋阀中的自旋弛豫，观察到单层石墨烯（SLG）和双层石墨烯（BLG）表现出截然不同的行为。在 SLG 中，自旋寿命（τ(s)）随载流子浓度的变化与动量散射时间（τ(p)）呈线性关系，表明在低温下 Elliot-Yafet（EY）自旋弛豫占主导地位。在 BLG 中，τ(s)和τ(p)表现出相反的依赖关系，这表明在低温下 Dyakonov-Perel 自旋弛豫占主导地位。不同的行为是由于 BLG 的增强屏蔽和/或表面灵敏度降低，这大大降低了杂质诱导的 EY 自旋弛豫。
