Reversal of the Circular Dichroism in Angle-Resolved Photoemission from ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$

Reversal of the Circular Dichroism in Angle-Resolved Photoemission from ${Bi}_{2} {Te}_{3}$

M. R. Scholz, J. Sánchez-Barriga, J. Braun, D. Marchenko, A. Varykhalov, M. Lindroos, Yung Jui Wang, Hsin Lin, A. Bansil, J. Minár, H. Ebert, A. Volykhov, L. V. Yashina, and O. Rader

Phys. Rev. Lett. 110, 216801 – Published 22 May 2013

Abstract

The helical Dirac fermions at the surface of topological insulators show a strong circular dichroism which has been explained as being due to either the initial-state spin angular momentum, the initial-state orbital angular momentum, or the handedness of the experimental setup. All of these interpretations conflict with our data from ${Bi}_{2} {Te}_{3}$ which depend on the photon energy and show several sign changes. Our one-step photoemission calculations coupled to ab initio theory confirm the sign change and assign the dichroism to a final-state effect. Instead, the spin polarization of the photoelectrons excited with linearly polarized light remains a reliable probe for the spin in the initial state.

Received 4 July 2012

DOI:https://doi.org/10.1103/PhysRevLett.110.216801

Authors & Affiliations

M. R. Scholz^1,*, J. Sánchez-Barriga¹, J. Braun², D. Marchenko¹, A. Varykhalov¹, M. Lindroos³, Yung Jui Wang⁴, Hsin Lin⁴, A. Bansil⁴, J. Minár², H. Ebert², A. Volykhov⁵, L. V. Yashina⁵, and O. Rader¹

¹Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
²Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, 81377 München, Germany
³Institute of Physics, Tampere University of Technology, P.O. Box 692, 33101 Tampere, Finland
⁴Physics Department, Northeastern University, Boston, Massachusetts 02115, USA
⁵Department of Chemistry, Moscow State University, Leninskie Gory 1/3, 119992 Moscow, Russia