BULK AND SURFACE ELECTRONIC STATES OF ORDERED Cu3Au(001): AN ANGLE-RESOLVED PHOTOEMISSION INVESTIGATION

Abstract

We have performed an angle-resolved ultraviolet photoemission spectroscopy (ARUPS) investigation of ordered Cu 3Au(001) at room temperature using He resonance and synchrotron radiation. The positions of upper Cu -like bulk bands near the center Γ of the bulk Brillouin zone (BZ) and the dispersion of the upper sp band along the A line have been determined using bulk-sensitive photon energies 10 eV≤hν≥15 eV. Except for a downward shift, the calculated bulk bands are in excellent agreement with experiment. Around the centers [Formula: see text] of the surface BZ, we have identified three new surface states in the energy region of the Au-like states and several surface-sensitive features in the Cu -like region below the known surface state on top of the Cu-like bulk d bands. These states strongly contribute to the ARUPS spectra for hν≥20 eV. The wealth of surface features found is in overall agreement with a recent surface electronic structure calculation [S. Halilov, H. Gollisch, E. Tamura and R. Feder, J. Phys.: Condens. Matter5, 4711 (1993)]. More detailed information is obtained by comparing the experimental spectra with theoretical ones calculated by a relativistic one-step model formalism.