On the interpretation of spin-polarized electron energy loss spectra

We study the origin of the structure in the spin-polarized electron energy loss spectroscopy (SPEELS) spectra of ferromagnetic crystals. Our study is based on a 3d tight-binding Fe model, with constant onsite Coulomb repulsion U between electrons of opposite spin. We find it is not the total density of Stoner states as a function of energy loss which determines the response of the system in the Stoner region, as usually thought, but the densities of Stoner states for only a few interband transitions. Which transitions are important depends ultimately on how strongly umklapp processes couple the corresponding bands. This allows us to show, in particular, that the Stoner peak in SPEELS spectra does not necessarily indicate the value of the exchange splitting energy. Thus, the common assumption that this peak allows us to estimate the magnetic moment through its correlation with exchange splitting should be reconsidered, both in bulk and surface studies. Furthermore, we are able to show that the above mechanism is one of the main causes for the typical broadness of experimental spectra. Finally, our model predicts that optical spin waves should be excited in SPEELS experiments.Comment: 11 pages, 7 eps figures, REVTeX fil

Resonant Auger spectroscopy at the L2,3 shake-up thresholds as a probe of electron correlation effects in nickel

The excitation energy dependence of the three-hole satellites in the L3-M4,5M4,5 and L2-M4,5M4,5 Auger spectra of nickel metal has been measured using synchrotron radiation. The satellite behavior in the non-radiative emission spectra at the L3 and L2 thresholds is compared and the influence of the Coster-Kronig channel explored. The three-hole satellite intensity at the L3 Auger emission line reveals a peak structure at 5 eV above the L3 threshold attributed to resonant processes at the 2p53d9 shake-up threshold. This is discussed in connection with the 6-eV feature in the x-ray absorption spectrum.Comment: 8 pages, 4 figures; http://prb.aps.org/abstract/PRB/v58/i7/p3677_

Evidence for

The electronic structure of the layered compound 1T-\chem{TiTe_2}, before and after deposition of \chem{Rb}, was studied by angle-resolved photoelectron spectroscopy. \chem{Rb} 4p core-level spectra were found to consist of two spin-orbit doublets, of which one could be unambiguously attributed to intercalated \chem{Rb}. Valence band spectra, which were compared with band structure calculations, provided further support that \chem{Rb} was intercalated, in conflict with recent claims. Possible explanations of the conflicting results are discussed

Windkraftanlage H-ROTOR: Erfahrungen, Aktuelles und Ausblick

Es wird ein Rotor fuer Windkraftanlagen vorgestellt, der aus geraden Blaettern mit konstantem Profil, den Blatthalterungen, der Nabe und dem in den Stahlbau integrierten Ring eines Magnetgenerators besteht. Getriebe, Blattverstellung und Windrichtungsnachfuehrung entfallen. Da der Rotor fuer eine niedrige Blattgeschwindkeit ausgelegt ist, faellt zudem die Schallemission gering aus. Der Turb wird vorteilhaft als Dreibein gestaltet. Dies fuehrt dazu, dass nur Vertikal- und Horizontalkraefte in den Boden abgesetzt werden und die Standsicherheit erhoeht wird. (BWI)A rotor for wind power plants with the integral parts straight blades, a constant profile section, blade supports, hub, and the ring of a 'magnetic generators', integrated into the steel structure, is presented. Gearing, blade adjustment devices and wind direction guidance are not necessary. As the rotor is designed for a low blade velocity the sound emission is low. The turb is preferably a three-legged construction. This means that only vertical and horizontal forces are transferred into the ground and thus an increased stability is obtained. (BWI)SIGLEAvailable from TIB Hannover: D.Dt.F.QN1(6,26) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

3D unoccupied band structure of graphite by very-low-energy electron diffraction

3D unoccupied band structure of graphite by very-low-energy electron diffraction / R. Claessen ... - In: Applied surface science. 162. 2000. S. 508-51

Three-dimensional unoccupied band structure of graphite

Three-dimensional unoccupied band structure of graphite : very-low-energy electron diffraction and band calculations / R. Claessen ... - In: Physical review. B. 61. 2000. S. 4994-500