Title: Origin of spin-polarized photocurrents in the topological surface states of Bi2 Se3
Other Titles: Spin-polarizované fotoproudy v topologických povrchových stavech Bi 2 Se 3
Authors: Ketterl, A. S.
Otto, Sebastian
Bastian, M.
Andres, Beatrice
Gahl, Cornelius
Minár, Jan
Ebert, Hubert
Braun, Jürgen
Tereshchenko, Oleg Evgenievich
Kokh, Konstantin A.
Fauster, Thomas
Weinelt, Martin
Citation: KETTERL, A. S., OTTO, S., BASTIAN, M., ANDRES, B., GAHL, C., MINÁR, J., EBERT, H., BRAUN, J., TERESHCHENKO, O. E., KOKH, K. A., FAUSTER, T., WEINELT, M. Origin of spin-polarized photocurrents in the topological surface states of Bi2 Se3. Physical Review B, 2018, roč. 98, č. 15, s. [1-6]. ISSN 2469-9950.
Issue Date: 2018
Publisher: American Physical Society
Document type: článek
URI: 2-s2.0-85054573045
ISSN: 2469-9950
Keywords: ARPES, topologické izolatory, KKR
Keywords in different language: ARPES, topological insulators, KKR
Abstract: Študovali sme spinovo polarizované foroprúdy v topologickom materiály Bi2Se3. Za pomoci 2PPE ARPES a teoretickými výpočtamy sme zistili že obecně platí, že trojnásobně symetrický dichroický signál nepodporuje jednosměrné fotoproudy. Nicméně, zbytková asymetrie až do 3,5% v našich fotoemisních spektrech je kompatibilní s dříve pozorovanými helickými efektami.
Abstract in different language: For the generation of spin-polarized photocurrents in topological insulators, a coupling between photon angular momentum and electron spin is often assumed. Such a coupling seems to be supported by dichroism reported in E(ky)-intensity maps in photoemission. We show in three dimensional two-photon photoemission and one-step photoemission calculations that the circular dichroism is in fact threefold in E(kx,k y) maps although it may appear antisymmetric in E(ky). The threefold symmetry is inconsistent with the previously assumed coupling between photon momentum and electron’s chiral spin via the orbital momentum. Instead it reflects the surface point group. The only antisymmetric patterns appear in the energy range in which surface and bulk states hybridize. In general, a threefold-symmetric dichroic signal does not support unidirectional photocurrents. Nevertheless, the residual asymmetry of up to 3.5% in our photoemission spectra is compatible with previously observed helicity-dependent photocurrents.
Rights: © American Physical Society
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