Band-Resolved Imaging of Photocurrent in a Topological Insulator
Band-Resolved Imaging of Photocurrent in a Topological Insulator
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DOI：
10.1103/physrevlett.122.167401
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发表时间：
2019-04-24
影响因子：
8.6
通讯作者：
Shen, Z. -X.
中科院分区：
文献类型：
--
作者：
Soifer, H.;Gauthier, A.;Shen, Z. -X.
我们通过时间和角度分辨光电子能谱研究了拓扑绝缘体Bi2Se3中光电流产生的微观起源。我们的图像的未占用的能带结构，因为它的演变后，圆偏振光激发和观察动量空间中的非对称电子人口，这是一个光电流的光谱签名。通过分析人口的上升时间，我们确定哪些占用和未占用的电子状态耦合的光激发。我们的结论是，光电流只能通过耦合到自旋轨道织构态的共振光学跃迁激发。我们的工作提供了一个微观的理解，如何控制系统中的光电流与自旋轨道耦合和破坏反转对称性。
We study the microscopic origins of photocurrent generation in the topological insulator Bi2Se3 via time- and angle-resolved photoemission spectroscopy. We image the unoccupied band structure as it evolves following a circularly polarized optical excitation and observe an asymmetric electron population in momentum space, which is the spectroscopic signature of a photocurrent. By analyzing the rise times of the population we identify which occupied and unoccupied electronic states are coupled by the optical excitation. We conclude that photocurrents can only be excited via resonant optical transitions coupling to spin-orbital textured states. Our work provides a microscopic understanding of how to control photocurrents in systems with spin-orbit coupling and broken inversion symmetry.