Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 18: Spin-orbit interaction
O 18.2: Vortrag
Montag, 26. März 2012, 16:15–16:30, A 060
Tl/Si(111) - Rotation of the Rashba spin perpendicular to the surface - The unoccupied electronic structure — •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
Tl/Si(111) exhibits an occupied Rashba-split surface state with a peculiar spin structure in reciprocal space [1]. Along the ΓK direction of the hexagonal two-dimensional surface Brillouin zone the spin polarization is rotating from the normal Rashba direction to the direction perpendicular to the surface. This is due to a spin frustration at the K point and can be simply understood as a consequence of the 2D symmetry of the hexagonal system. Our spin-resolved inverse photoemission study reveals an unoccupied spin-orbit split surface state along ΓK with the same out-of-plane rotation of the spin polarization. Remarkably, at the K point the two spin components are split in energy by more than 0.5 eV, whereas the lower surface band approaches the Fermi level. This gives rise to a nearly complete spin polarization at EF. As the out-of-plane spin polarization is always negative for K and positive for K′, interesting transport properties can be expected. Our results are supported and discussed on the basis of calculations within
the LDA and the GW approximation including spin-orbit coupling.
K. Sakamoto et al., Phys. Rev. Lett. 102, 096805 (2009)