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O: Oberflächenphysik
O 19: Electronic structure II
O 19.4: Vortrag
Dienstag, 28. März 2006, 12:00–12:15, WIL A317
Unoccupied surface state on Pt(111) revealed by scanning tunneling spectroscopy — •Jens Wiebe1, Focko Meier1, Katsushi Hashimoto1, Gustav Bihlmayer2, Stefan Blügel2, Paolo Ferriani1, Stefan Heinze1, and Roland Wiesendanger1 — 1Institute of Applied Physics, Hamburg University, D-20355 Hamburg, Germany — 2Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425 Jülich, Germany
Surface states are known to play a crucial role in chemistry, magnetism and for the growth properties of surfaces of noble metals and late fcc transition-metals (Ni, Pd, Pt). For noble-metal (111) surfaces it is well known that a partly occupied surface state resides far inside the projected bulk sp-band gap. The situation is more complex for the transition-metals. Ni(111) has a partly occupied surface state, while the corresponding surface state on Pd(111) is unoccupied and far above the Fermi energy EF. For Pt(111) the situation was controversial so far.
We measured the dispersion of an unoccupied surface state on Pt(111) by imaging scattering states at point defects and step edges using scanning tunneling spectroscopy. By comparison to first-principles electronic structure calculations the state is assigned to an sp-derived surface band at the lower edge of the projected bulk band-gap. In dI/dV(V)-curves, the onset of the surface-state band appears as a rather broad feature. Its shape results from two spin-orbit split branches with nearly linear dispersion, one of them merging into bulk states at higher energies. We found no indications for a surface state below EF.[1]
[1] J. Wiebe, et al., Phys. Rev. B 72, 193406 (2005)