论文标题
拓扑绝缘子表面状态的线性光钙化效应
Linear photogalvanic effect in surface states of topological insulators
论文作者
论文摘要
线性光钙化效应的理论是针对三维拓扑绝缘子表面状态之间的直接光学转变的。计算了光电流由光的极化平面的取向，并由二维载体的能量分散剂引起的光电流。结果表明，光学跃迁过程中粒子波袋的坐标偏移引起的偏移贡献以及由光吸收和散射散射引起的弹道贡献，通常具有相同的数量级。由于拓扑表面状态的电子孔不对称性，与移位光电流相比具有频率依赖性，因此存在弹道贡献。在非线性中，由于直接光学转变的饱和而出现在光强度状态下，弹道贡献占主导地位。光电流对非线性状态中极化平面方向的非平凡依赖性似乎完全是由于弹道贡献。我们的发现允许在实验中分离对线性光藻电流的弹道和转移贡献。
Theory of the Linear photogalvanic effect is developed for direct optical transitions between surface states of three-dimensional topological insulators. The photocurrent governed by the orientation of the polarization plane of light and caused by the warping of the energy dispersion of two-dimensional carriers is calculated. It is shown that both the shift contribution caused by coordinate shifts of the particle wavepackets during the optical transitions and the ballistic contribution caused by interference of the optical absorption and scattering by disorder have generally the same order of magnitude. The ballistic contribution is present owing to electron-hole asymmetry of topological surface states and has a frequency dependence in contrast to the shift photocurrent. In the nonlinear in the light intensity regime appearing due to saturation of the direct optical transitions the ballistic contribution dominates. The nontrivial dependence of the photocurrent on the polarization plane orientation in the nonlinear regime appears solely due to the ballistic contribution. Our findings allow separating the ballistic and shift contributions to the Linear photogalvanic current in experiments.
