论文标题
边缘光电流由双层石墨烯中的THZ电场驱动
Edge photocurrent driven by THz electric field in bi-layer graphene
论文作者
论文摘要
我们报告了Terahertz激光辐射对双层石墨烯激发的边缘电流的观察。我们表明，当前一代属于电场现象中的二阶等级，并由THZ电场极化平面的方向控制。另外，将垂直于石墨烯平面的小磁场应用导致极化依赖性的相移。增加磁场强度，与在相同条件下测得的零磁场的电流相比，与Shubnikov-de-HaaS效应和振幅相一致的周期与Shubnikov-de-HaaS效应和振幅相一致的周期开始展示1/B-磁磁镜。显微镜理论表明，电流是由载体的均值路径和高频电场的筛选长度限制在边缘附近形成的。电流起源于自由载体动量的比对和电荷在边缘的动态积累，其中P-对称性自然损坏。观察到的光电流的磁镜归因于Landau水平的形成。
We report on the observation of edge electric currents excited in bi-layer graphene by terahertz laser radiation. We show that the current generation belongs to the class of second order in electric field phenomena and is controlled by the orientation of the THz electric field polarization plane. Additionally, applying a small magnetic field normal to the graphene plane leads to a phase shift in the polarization dependence. Increasing the magnetic field strength, the current starts to exhibit 1/B-magnetooscillations with a period consistent with that of the Shubnikov-de-Haas effect and amplitude by an order of magnitude larger as compared to the current at zero magnetic field measured under the same conditions. The microscopic theory developed shows that the current is formed in the edges vicinity limited by the mean-free path of carriers and the screening length of the high-frequency electric field. The current originates from the alignment of the free carrier momenta and dynamic accumulation of charge at the edges, where the P-symmetry is naturally broken. The observed magnetooscillations of the photocurrent are attributed to the formation of Landau levels.
