Dresden 2006 – scientific programme

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MA: Magnetismus

MA 12: Kondo / Heavy Fermions

MA 12.2: Talk

Monday, March 27, 2006, 16:45–17:00, HSZ 403

High-resolution Fermi-Edge and energy dependent photoemission spectra of Fe_1−xCo_xSi — •D. Zur¹, I. Jursic¹, D. Menzel¹, L. Patthey², and J. Schoenes¹ — ¹Institut für Physik der Kondensierten Materie, TU Braunschweig, Germany — ²Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland

The interest on FeSi is renewed because of similarities with some rare-earth compounds known as Kondo insulators. In spite of several photoemission investigations, the size of the gap is still not clear. In addition, the influence on the electronic structure by doping with a 3d transition metal is interesting due to the changes in electronic and magnetic properties. We present high resolution photoemission spectra at 11 K of the Fermi edge of Fe_1−xCo_xSi crystals with 0, 5 and 20 at.% Co, using synchrotron radiation at the SLS. Photon energies of 21.2 eV and 40.8 eV have been used. A gap of about 80 meV has been found, which is consistent with some theoretical predictions. This gap closes with increasing Co concentrations. Furthermore, changes in the electronic structure owing to different Co concentrations have been studied with angle- and photoenergy-resolved photoemission.