Hébert, C.

Schöne, W.

Su, D.

English

MPG.PuRe

Experimental and theoretical Determination of Low electron Energy Loss spectra of Ag and Ru

Submitted to Ultramicroscopy 2005Preprint of the Department of Inorganic Chemistry, Fritz-Haber-Institute of the MPG (for personal use only) (www.fhi-berlin.mpg.de/ac)Experimental and theoretical Determination of Low electron Energy Loss spectra of Ag and RuC. Heberta, W.-D. Schöneb, D. S. SucaInstitut für Festkörperphysik, Technische Universität Wien, A-1040 WienbDepartment of Physical Chemistry, Fritz-Haber- Institut of the Max-Planck-Society, Faradayweg 4-6, D-14195 BerlincDepartment of Inorganic Chemistry, Fritz-Haber- Institut of the Max-Planck-Society, Faradayweg 4-6, D-14195 BerlinAbstractWe show the experimental and calculated q-dependent low energy loss electron energy loss spectrum of Ru and Ag. The spectra were calculated within the time-dependent density-functional theory including local-field effects. For Ag, the momentum transfer was parallel to the (110) direction. For Ru the 3 main directions (010), (110) and (001) were investigated. The agreement between theory and experiment is very good for Ag and momentum transfers parallel to the (001) direction of Ru. For momentum transfers parallel to the in-plane directions (110) and (010) the agreement for Ru is not satisfactory, which could be attributed to relativistic effects or strong localization of the 4d states of Ru.Key words: Electron Energy Loss spectroscopy, linear response

Hébert, Cécile

Schöne, Wolf-Dieter

Su, Dang Sheng

Max Planck Society eDoc Server

Preprint of the Department of Inorganic Chemistry, Fritz-Haber-Institute of the MPG (for personal use only) (www.fhi-berlin.mpg.de/ac)Experimental and Theoretical Determination of Low Electron Energy Loss Spectra of Ag and RuD. S. Su1, W.-D. Schöne1, C. Hébert21 Fritz-Haber-Institute of the Max Planck Society, Faradayweg 4-6, D-14195 Berlin, Germany2 Institute for Solid State Physics, Technical University of Vienna, Wiedner Hauptstrase 8-10, A-1040 Wien, AustriaVery complex materials and highly correlated electronic systems in reduced dimensions become currently one of the main investigation topics in condensed matter physics. However, understanding the behavior of these new and exciting materials requires a detailed understanding of electronic correlation. Comparatively simple systems, e.g., noble metals in the crystalline phase, have therefore gained renewed interest. We present in this work the results of the dynamical electronic response of Ag and Ru determined by EELS-experiment and by ab-initio calculations. The comparison of the theoretical calculation with the experimental data allow the analysis of the many-body and crystal local-field effects.  The calculations are carried out in the framework of the Random Phase Approximation (RPA) and the time-dependent local density approximation (TDLDA), which also accounts for vertex corrections. Experiments were performed on a Philips CM 200 FEG TEM and on a TG 200 FEG TEM, operated at 200 kV. A GATAN imaging filter was used to record the EEL-spectra. The Ag and Ru single crystals were prepared by polishing and ion-milling until electron transparency. In diffraction mode, the pattern is moved over the entrance aperture of the energy filter to choose the demanded q values. The recording time varies from 10 to 60 s according to the chosen momentum transfer.FIG. 1. left: Experimental and theoretical spectrum of Ag; right: Influence of crystal local-field effects on the density-response function. Both experiment and theoretical calculations show a q-dependent dynamic response in single crystal Ag and Ru. The results for q =(½, ½, 0) of Ag are displayed in Fig. 1 (left). While the spectrum feature between 20 to 40 eV are found in both results, the maching for energy region less than 20 eV is not satisfying. The imaginary part of the density-response function of the G=G´=0 is also presented in Fig. 1 (right). Details about the electronic response at other q values and in Ru will be presented.References[1] This research was initiated and motivated by Dr. Walter Ekardt.  

Experimental and Theoretical Determination of Low Electron Energy Loss Spectra of Ag and Ru

http://hdl.handle.net/11858/00-001M-0000-0011-063E-D

Experimental and theoretical Determination of Low electron Energy Loss spectra of Ag and Ru

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