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ISSN - 10980121, Physical Review B - Condensed Matter and Materials Physics, 2016, vol. 93, 24, p. -

Photoelectron spin polarization in the Bi2Te3 (0001) topological insulator: Initial- and final-state effects in the photoemission process

Seibel Christoph, Braun Jürgen, Maaß Henriette, Bentmann Hendrik, Minár Jan, Kuznetsova Tatyana V., Kokh Konstantin A., Tereshchenko Oleg E., Okuda Taichi, Ebert Hubert, Reinert Friedrich

© 2016 American Physical Society.The photoelectron spin polarization in angle-resolved photoemission from the topological surface state in Bi2Te3(0001) has been investigated in a combined experimental and theoretical study. Our measurements show significant photon-energy-dependent deviations in the three-dimensional spin polarization of the photoelectron when compared to the expected intrinsic spin polarization of the surface state. The experimental observations are in line with relativistic one-step photoemission calculations. Our theoretical analysis confirms that spin-orbit coupling in the initial-state wave functions in combination with the dipole selection rules strongly influences the photoelectron spin polarization. Furthermore, spin-dependent final-state effects are found to influence the spin polarization significantly. A quantitative access to the three-dimensional spin-polarization vector in topological insulators is thus challenged by a complex interplay of initial- and final-state effects in the photoemission process.