Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 1: Hauptvortrag Hofmann

O 1.1: Hauptvortrag

Montag, 8. März 2004, 09:30–10:15, H36

Electron-phonon coupling and spin-orbit splitting in quasi two-dimensional metals: the surfaces of Bi — •Philip Hofmann — Institute for Storage Ring Facilities, University of Aarhus, Ny Munkegade, DK-8000 Aarhus C

Bi is a group V semimetal with a very low density of states at the Fermi level. Several low-index surfaces of Bi support metallic surface states which turn them into considerably better metals than the bulk. Indeed, it is fair to view these surfaces as quasi two-dimensional metals on an almost insulating substrate. We have studied the effect of the electron-phonon coupling and the spin-orbit interaction on such systems. For the former we find that the coupling strength depends strongly on the binding energy of the states and it is therefore not possible to determine the electron-phonon mass enhancement parameter λ from the temperature-dependent width of surface states at higher binding energies. For all Bi surfaces the spin-orbit splitting of the bands is very large and dominates the two-dimensional dispersion. The consequences of this on phenomena like screening or the formation of charge density waves will be discussed.