Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 55: Electronic Structure and Spin-Orbit Interaction II

O 55.8: Vortrag

Mittwoch, 13. März 2013, 17:45–18:00, H42

Unoccupied surface state of Tl/Si(111): Rotating spin and giant splitting — •Sebastian D. Stolwijk¹, Kazuyuki Sakamoto², Anke B. Schmidt¹, Peter Krüger³, and Markus Donath¹ — ¹Physikalisches Institut, Westfälische Wilhelms-Universität Münster — ²Graduate School of Advanced Integration Science, Chiba University, Japan — ³Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster

Spin-resolved inverse photoemission experiments reveal the unoccupied electronic structure along the ΓK direction of the Tl/Si(111)-(1× 1) surface. Our recently developed ROtatable Spin-polarized Electron source (ROSE) enables measurements of the in-plane and out-of-plane component of the polarization vector. With this, we identify a spin-orbit split surface state, whose polarization vector rotates from the usual Rashba direction to the direction perpendicular to the surface upon approaching the K point. This effect can be simply understood as a consequence of the 2D symmetry of the hexagonal system [1]. Remarkably, the spin-orbit split surface state shows almost complete out-of-plane polarization with opposing sign at the K and K^′ point. Moreover, the spin-orbit split surface state exhibits a giant splitting in energy of more than 0.5 eV. Our results are supported and discussed on the basis of calculations within the GW approximation including spin-orbit coupling. Charge distributions of the surface state reveal that the giant splitting is due to a strong localization close to the Tl atom.
K. Sakamoto et al., Phys. Rev. Lett. 102, 096805 (2009)