Reversal of the circular dichroism in the angle-resolved photoemission from Bi2Te3
M. R. Scholz, J. S\'anchez-Barriga, J. Braun, D. Marchenko, A., Varykhalov, M. Lindroos, Yung Jui Wang, Hsin Lin, A. Bansil, J. Min\'ar, H., Ebert, A. Volykhov, L. V. Yashina, and O. Rader
TL;DR
This study investigates the circular dichroism in angle-resolved photoemission from Bi2Te3, revealing it is primarily due to final-state effects rather than initial-state spin or orbital angular momentum, with implications for spin measurements.
Contribution
The paper demonstrates that the reversal of circular dichroism in Bi2Te3 is caused by final-state effects, challenging previous interpretations based on initial-state properties.
Findings
Sign change in dichroism with photon energy
Dichroism attributed to final-state effects
Spin polarization remains a reliable initial-state probe
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 Bi2Te3 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. The spin polarization of the photoelectrons, instead, remains a reliable probe for the spin in the initial state.
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