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Electronic excitation spectra of the five-orbital Anderson impurity model: From the atomic limit to itinerant atomic magnetism

  • Huang, Li Department of Physics, University of Fribourg, Switzerland
  • Wehling, Tim O. Institute for Theoretical Physics, Bremen Center for Computational Materials Science, University of Bremen, Germany
  • Werner, Philipp Department of Physics, University of Fribourg, Switzerland
    05.06.2014
Published in:
  • Physical Review B. - 2014, vol. 89, no. 24, p. 245104
English We study the competition of Coulomb interaction and hybridization effects in the five-orbital Anderson impurity model by means of continuous time quantum Monte Carlo, exact diagonalization, and Hartree-Fock calculations. The dependence of the electronic excitation spectra and thermodynamic ground-state properties on the hybridization strength and the form of the Coulomb interaction is systematically investigated for impurity occupation number N≈6. With increasing hybridization strength, a Kondo resonance emerges, broadens and merges with some of the upper and lower Hubbard peaks. Concomitantly, there is an increase of charge fluctuations at the impurity site. In contrast to the single-orbital model, some atomic multiplet peaks and exchange split satellites persist despite strong charge fluctuations. We find that Hund's coupling leads to a state that may be characterized as an itinerant single atom magnet. As the filling is increased, the magnetic moment decreases, but the spin freezing phenomenon persists up to N≈8. When the hybridization is weak, the positions of atomic ionization peaks are rather sensitive to shifts of the impurity on-site energies. This allows to distinguish atomic ionization peaks from quasiparticle peaks or satellites in the electronic excitation spectra. On the methodological side we show that a comparison between the spectra obtained from Monte Carlo and exact diagonalization calculations is possible if the charge fluctuations are properly matched.
Faculty
Faculté des sciences et de médecine
Department
Département de Physique
Language
  • English
Classification
Physics
License
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Persistent URL
https://folia.unifr.ch/unifr/documents/303762
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