Regensburg 2004 – wissenschaftliches Programm
O 11.11: Vortrag
Montag, 8. März 2004, 18:15–18:30, H44
Surface state splitting in thin Mg films — •Frederik Schiller1,2, Vito Servedio3, and Clemens Laubschat1 — 1Institut für Festkörperphysik, TU Dresden, D-01062 Dresden, Germany — 2Donostia International Physics Center, E-20018 Donostia/San Sebastian, Spain — 3Sezione INFM and Dip. di Fisica, Università “La Sapienza”, P. le A. Moro 2, I-00185 Roma, Italy
Thin Mg films deposited onto a W(110) surface show a hexagonal close-packed structure in (0001) direction. Photoemission spectra in normal-emission geometry reveal a surface state inside the Shockley-inverted energy gap and quantum well oscillations on both sides of the gap.
We study the evolution of the surface and the quantum well states depending on the emission direction and Mg thickness. For Mg films exceeding 12 ML, both, surface and quantum well states disperse parabolic-like around the Γ point of the surface Brillouin zone. In thinner films, however, in off-normal geometry the surface state splits into several branches with different effective masses. We ascribe this phenomenon to the lattice mismatch between the Mg film and the underlying W substrate that may lead (i) to distortions of the surface geometry and (ii) variations of the confinement conditions at the Mg/W interface that reveal a periodicity different from that of the Mg lattice.