Berlin 2005 – wissenschaftliches Programm
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O: Oberflächenphysik
O 52: Elektronische Struktur IV
O 52.3: Vortrag
Mittwoch, 9. März 2005, 11:15–11:30, TU EB301
Fermi contours of a quasi-periodic 1-D film structure — •P. Moras1, L. Ferrari1, S. Gardonio1, C. Carbone1, J. Fuji2, W. Theis3, and K. Horn4 — 1Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Trieste, Italy — 2Laboratorio TASC, I.N.F.M, Trieste, Italy — 3Freie Universitaet, Berlin, Germany — 4Fritz-Haber-Institut, MPG, Berlin, Germany
Ag(111) films grown on GaAs(110) present in high-resolution STM images a quasi-periodic distribution of stripes running along the GaAs[1-10]-direction with two characteristic separations of 17 Å and 12 Å. The resulting one-dimensional superstructure can be described by a golden-mean Fibonacci sequence with a coherence length of about 125 Å. Angle-resolved photoemission has been used to examine the spectral functions of the sp-derived Ag electronic states as a function of the photoelectron momentum. While the dispersion of the Ag sp-quantum well states along the stripe direction is close to a free-electron-like parabola, it displays flatter bands and a complex branching structure perpendicularly to them. A close correspondence is found between the incommensurate wave vectors derived from the LEED pattern and those characterizing the Fermi contours of the Ag films in the two-dimensional reciprocal space.