Chiral orbital-angular momentum in the surface states of Bi 2Se 3

Seung Ryong Park, Jinhee Han, Chul Kim, Yoon Young Koh, Changyoung Kim, Hyungjun Lee, Hyoung Joon Choi, Jung Hoon Han, Kyung Dong Lee, Nam Jung Hur, Masashi Arita, Kenya Shimada, Hirofumi Namatame, Masaki Taniguchi

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Abstract

We performed angle-resolved photoemission (ARPES) experiments with circularly polarized light and first-principles density functional calculation with spin-orbit coupling to study surface states of a topological insulator Bi 2Se 3. We observed circular dichroism (CD) as large as 30% in the ARPES data with upper and lower Dirac cones showing opposite signs in CD. The observed CD is attributed to the existence of local orbital-angular momentum (OAM). First-principles calculation shows that OAM in the surface states is significant and is locked to the electron momentum in the opposite direction to the spin, forming chiral OAM states. Our finding opens a new possibility for strong light-induced spin-polarized current in surface states. We also provide a proof for local OAM origin of the CD in ARPES.

Original languageEnglish
Article number046805
JournalPhysical review letters
Volume108
Issue number4
DOIs
Publication statusPublished - 2012 Jan 25

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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    Park, S. R., Han, J., Kim, C., Koh, Y. Y., Kim, C., Lee, H., Choi, H. J., Han, J. H., Lee, K. D., Hur, N. J., Arita, M., Shimada, K., Namatame, H., & Taniguchi, M. (2012). Chiral orbital-angular momentum in the surface states of Bi 2Se 3 Physical review letters, 108(4), [046805]. https://doi.org/10.1103/PhysRevLett.108.046805