Edge photocurrent driven by terahertz electric field in bilayer graphene
Edge photocurrent driven by terahertz electric field in bilayer graphene
复制标题
双层石墨烯中太赫兹电场驱动的边缘光电流
DOI：
10.1103/physrevb.102.045406
复制
发表时间：
2020
影响因子：
3.7
通讯作者：
Candussio S
中科院分区：
文献类型：
--
作者：
Candussio S
我们报告的观察边缘电流激发双层石墨烯太赫兹激光辐射。我们表明，电流产生属于二阶电场现象的类，并控制太赫兹电场极化平面的取向。另外，施加垂直于石墨烯平面的小磁场导致偏振依赖性的相移。随着磁场强度的增加，电流开始发生磁振荡，其周期与Shubnikov-de哈斯效应的周期一致，振幅比相同条件下零磁场下测得的电流大一个数量级。微观理论表明，电流是在边缘附近形成的，受到载流子平均自由程和高频电场屏蔽长度的限制。电流来源于自由载流子动量的排列和电荷在边缘的动态积累，对称性自然被打破。所观察到的光电流的磁振荡归因于朗道能级的形成。
We report on the observation of edge electric currents excited in bilayer 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. With increasing the magnetic field strength, the current starts to exhibit-magneto-oscillations 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 edge's 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-symmetry is naturally broken. The observed magneto-oscillations of the photocurrent are attributed to the formation of Landau levels.