Band-Resolved Imaging of Photocurrent in a Topological Insulator

H. Soifer, A. Gauthier, A. F. Kemper, C. R. Rotundu, S. L. Yang, H. Xiong, D. Lu, M. Hashimoto, P. S. Kirchmann, J. A. Sobota, Z. X. Shen

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Article number167401
JournalPhysical Review Letters
Issue number16
StatePublished - 24 Apr 2019
Externally publishedYes


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