Possible multi-orbital ground state in CeCu<sub>2</sub>Si<sub>2</sub>

ORAL

Abstract

The crystal-field ground state wave function of CeCu2Si2 has been investigated with linear polarized M-edge x-ray absorption spectroscopy from 250 mK to 250 K, thus covering the superconducting (Tc = 0.6 K), the Kondo (TK ≈ 20 K) as well as the Curie-Weiss regime. The comparison with full-multiplet calculations shows that the temperature dependence of the experimental linear dichroism is well explained with a Γ7(1) crystal-field ground state and the thermal population of excited states at around 30 meV. The crystal-field scheme does not change throughout the entire temperature range thus making the scenario of orbital switching unlikely. Spectroscopic evidence for the presence of the Ce 4f 0 configuration in the ground state is consistent with the possibility of a multi-orbital character of the ground state. We estimate from the Kondo temperature and crystal-field splitting energies that several percents of the higher lying Γ6 state and Γ7(2) crystal-field states are mixed into the primarily Γ7(1) ground state. This estimate is also supported by re-normalized band-structure calculations that use the experimentally determined crystal-field scheme.

*Financial support of LabEx PALM (ANR-10- LABX-0039-PALM) and of DFG grants SE 1441-4-1 and SE 1441-5-1 is gratefully acknowledged

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Presenters

  • Andrea Marino

    • Max Planck Institute for Chemical Physics of Solids

Authors

  • Andrea Marino

    • Max Planck Institute for Chemical Physics of Solids

  • Andrea Amorese

    • Max Planck Institute for Chemical Physics of Solids
    • Max Planck Institute for Chemical Physics of Solids (Dresden, Germany)

  • Martin Sundermann

    • Max Planck Institute for Chemical Physics of Solids
    • Institute of Physics II, University of Cologne, Cologne, Germany

  • Kai Chen

    • Helmoltz-Zentrum Berlin fuer Materialien und Energie
    • Institute of Physics II, University of Cologne

  • zhiwei hu

    • Max Planck Institute for Chemical Physics of Solids

  • Fadi Choukani

    • Synchrotron SOLEIL

  • Philippe Ohresser

    • Synchrotron SOLEIL

  • Javier Herrero-Martín

    • ALBA Synchrotron Light Source
    • Synchrotron ALBA

  • Stefano Agrestini

    • Diamond Synchrotron Light Source
    • Diamond Light Source
    • Diamond Light Source, UK
    • ALBA Synchrotron Light Source

  • Chien-Te Chen

    • National Synchrotron Radiation Research Center
    • National Synchrotron Radiation Research Center (NSRRC)

  • Hong-Ji Lin

    • National Synchrotron Radiation Research Center

  • Maurits Wim Haverkort

    • Institute for Theoretical Physics, Heidelberg University
    • Heidelberg University
    • Institute for theoretical Physics, Heidelberg University (Germany)
    • Institute for theoretical Physics, University of Heidelberg

  • Silvia Seiro

    • Institue for Solid State Research, Leibniz Institute for Solid State and Materials Reasearch

  • Christoph Geibel

    • Max Planck Institute for Chemical Physics of Solids

  • Frank Steglich

    • Max Planck Institute for Chemical Physics of Solids

  • Liu Tjeng

    • Max Planck Institute for Chemical Physics of Solids
    • Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
    • Max Planck Institute for Chemical Physics of Solids (Dresden, Germany)
    • Max Planck Institute for Chemical Physics of Solids (MPI CPfS)
    • Max-Planck Institute for Chemical Physics of Solids

  • Gertrud Zwicknagl

    • Institute for Mathematical Physics, Technical University Braunschweig
    • Tech Univ Braunschweig

  • Andrea Severing

    • Institute of Physics II, University of Cologne
    • Intitute of Physics II, University of Cologne
    • University of Cologne
    • Institute of Physics II, University of Cologne (Germany)
    • Institute of Physics II, University of Cologne, Cologne, Germany