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

Paper SS1-ThM7
Auger Spectroscopy and the Electronic Structure of Quasicrystals

Thursday, November 1, 2001, 10:20 am, Room 121

Session: Quasicrystals
Presenter: V. Fournèe, Iowa State University
Authors: V. Fournèe, Iowa State University
J.W. Anderegg, Iowa State University
A.R. Ross, Iowa State University
T.A. Lograsso, Iowa State University
P.A. Thiel, Iowa State University
Correspondent: Click to Email
So far, the electronic structure of QC has been probed primarily by photoelectron and x-ray spectroscopies. These studies mainly focussed on the existence of a structure induced minimum of the density of states located at the Fermi level, the so-called pseudogap. Auger spectroscopy, on the other hand, can yield unique insight into important aspects of the electronic structure of alloys such as screening and electron correlation effects. Here we will present our experimental work on the transition metals LMM Auger lines in several quasicrystalline phases, the Al-Pd-Mn and Al-Cu-Fe icosahedral QCs and the Al-Ni-Co decagonal QC. This include the core-core-valence and the core-valence-valence Auger spectra. From the line shape, line splitting and energies of the Auger spectra, it is possible to derive empirical parameters correlated with the extent of quasiatomic or bandlike behavior, which depends on the relationship between the local DOS and the value of the on-site correlation energy. Our first results in the i-Al-Pd-Mn clearly shows that the Mn-L3M45M45 has a bandlike behavior and reflects the self-convolution of the Mn-3d valence band. The width of the Mn-3d band is quite narrow in the QC, as compared to pure Mn. We also found a decrease of the 3d-containing Auger transition rates in the QC relative to the metal. This could be due to an increased localization of the 3d states in the quasicrystals, that will lower the probability for a 3d electron to fill a 2p photohole. This is consistent with the reduction of the intrinsic width of the Mn 2p3/2 core level observed by photoemission spectroscopy.