Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 32: Spin-Orbit Interaction at Surfaces II
O 32.1: Vortrag
Dienstag, 15. März 2011, 11:15–11:30, WIL C307
Spin-orbit split occupied and unoccupied surface states of Bi alloys on Cu(111) and Ag(111) — •A. Akin Ünal1, Christian Tusche1, Francesco Bisio2, Aimo Winkelmann1, and Jürgen Kirschner1 — 1Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany — 2CNR-SPIN, Corso Perrone 24, I-16152 Genova, Italy
We investigated the electronic band structure of Bi surface alloys on Cu(111) and Ag(111) surfaces by one- and two-photon photoemission experiments (1PPE and 2PPE) excited by the second and fourth harmonics of a mode-locked Ti:sapphire femtosecond oscillator with photon energies of 3.1 eV and 6.0 eV. Occupied and unoccupied states can be respectively probed by 1PPE and 2PPE, providing comprehensive information on the electronic band structures. The negative electronic dispersions and Rashba-splittings of the partially-filled spz and of the unoccupied px py surface states were measured using our momentum microscope, which directly maps the parallel momentum component kx, ky of the photoelectrons as a function of energy without the need for sample or detector rotation. 1PPE experiments show that in the √3×√3-R30∘ Bi/Cu(111) system, the Fermi level is below the crossing point of the spin-split spz bands; however, in the case of Bi/Ag(111), the Fermi level lies above this crossing point. The 2PPE experiments, on the other hand, show the spin-splittings of the unoccupied px py states of both systems in the momentum space.