Regensburg 2007 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 22: FV intern Symposium: "Heusler Alloys"
Invited Talks Kübler/Yamamoto/Inomata/Silvia Picozzi

MA 22.8: Vortrag

Donnerstag, 29. März 2007, 13:00–13:15, H10

Electronic structure and high energy valenceband photoemission of Heusler compounds — •Gerhard H. Fecher and Claudia Felser — Institute for Inorganic and Analytical Chemistry, Johannes Gutenberg - Universität, 55099 Mainz, Germany

This work reports on high resolution photoelectron spectroscopy of the valence band of Co₂Mn_1−xFe_xSi (x=0,0.5,1) excited by photons of 8 keV energy. The measurements show a good agreement to calculations of the electronic structure using the LDA+U scheme. It is shown that the high energy spectra reveal the bulk electronic structure better compared to low energy XPS spectra. The high resolution measurements of the valence band close to the Fermi energy indicate the existence of the gap - or at least a pronounced minimum - in the minority states for all three alloys.

The role of the composition for the position of the Fermi energy and the stability of the half-metallic ferromagnetism is discussed for the iso-electronic Heusler compound Co₂FeAl_1−xSi_x. The energy dependence of high energy photoelectron spectroscopy will be discussed with an example of spectra taken at 1.2-5 keV from the C1_b compound CoTiSb.

(Financial support by the Deutsche Forschungsgemeinschaft in FG 559 (TP 7) is gratefully acknowledged.)