论文标题
Terahertz Photogalvanics在扭曲的双层石墨烯中，靠近第二个魔术角
Terahertz photogalvanics in twisted bilayer graphene close to the second magic angle
论文作者
论文摘要
我们报告了在扭曲的双层石墨烯（TBLG）中观察到的光子效应，扭曲角为0.6°。我们表明，TBLG的激发会导致光电流，其符号和大小通过辐射电场和光子螺旋度的方向控制。观察到的光电流为低扭曲角tblg中点组对称性的降低为最低的光电流提供了证据。开发的理论表明，电流是由陀螺仪TBLG中的不对称散射形成的。我们还检测到边缘附近形成的光藻电流。对于散装和边缘光电流，我们证明了栅极电压变化时明显振荡的出现。与振荡相关的栅极电压与电阻测量的峰良好。这些是通过TBLG中众多孤立带之间的频段间跃迁来很好地解释的。
We report on the observation of photogalvanic effects in twisted bilayer graphene (tBLG) with a twist angle of 0.6°. We show that excitation of tBLG bulk causes a photocurrent, whose sign and magnitude are controlled by orientation of the radiation electric field and the photon helicity. The observed photocurrent provides evidence for the reduction of the point group symmetry in low twist-angle tBLG to the lowest possible one. The developed theory shows that the current is formed by asymmetric scattering in gyrotropic tBLG. We also detected the photogalvanic current formed in the vicinity of the edges. For both, bulk and edge photocurrents, we demonstrate the emergence of pronounced oscillations upon variation of the gate voltage. The gate voltages associated with the oscillations coincide well with peaks in resistance measurements. These are well explained by inter-band transitions between a multitude of isolated bands in tBLG.
