IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Thursday Sessions
       Session SS1-ThM

Invited Paper SS1-ThM1
Peter Mark Memorial Award Lecture - Surface Preparation and Electronic Properties of d-AlNiCo

Thursday, November 1, 2001, 8:20 am, Room 121

Session: Quasicrystals
Presenter: E. Rotenberg, Lawrence Berkeley National Laboratory
Authors: E. Rotenberg, Lawrence Berkeley National Laboratory
W. Theis, Free University, Germany
K. Franke, Free University, Germany
K. Horn, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Germany
P. Gille, Maximilians-Universitat Munich, Germany
Correspondent: Click to Email
Apart from their striking structural properties, i.e. perfect long range order without translational symmetry, quasicrystals exhibit fascinating physical properties unlike those of ordinary metallic alloys. As the properties of all metals are determined by the valence states near the Fermi level, we have undertaken a program to prepare clean quasicrystalline surfaces and characterize these states by angle-resolved photoemission. The samples were characterized by ESCA, xray photoelectron diffraction (XPD) and LEED. Our k-dependent photoemission intensity maps from the tenfold and two inequivalent twofold surfaces from d-Al@sub 71.8@Ni@sub 14.8@Co@sub 13.4@ shows the existence of dispersing s-p- and d-derived valence states. We use an extension of the concept of the Brillouin zone in order to characterize the observed dispersion. Maps from all three surface orientations yield a consistent picture of free- electron-like constant energy surfaces in 3D k-space. We find the centers of these energy surfaces to be located at the positions of dominant electron diffraction spots as expected from the quasi-Brillouin zone model. Dispersion arises from delocalized quasicrystal valence states, while a large non-dispersing intensity in our spectra could be attributed to either localized states or scattering from the hierarchy of densely spaced Bragg planes in quasicrystals.