Orbitally controlled Kondo effect of Co ad-atoms on graphene

ORAL

Abstract

Based on ab-initio calculations we identify possible scenarios for the Kondo effect due to Co ad-atoms on graphene. For a Co atom absorbed on top of a carbon atom, the Kondo effect is quenched by spin-orbit coupling below an energy scale of $\sim \!\!15$\,K. For Co with spin $S=1/2$ located in the center of a hexagon, an SU(4) Kondo model describes the entanglement of orbital moment and spin at higher energies, while below $\sim 60$\,meV spin-orbit coupling leads to a more conventional SU(2) Kondo effect. The interplay of the orbital Co physics and the peculiar band-structure of graphene is directly accessible in Fourier transform tunneling spectroscopy or in the gate-voltage dependence of the Kondo temperature displaying a very strong, characteristic particle-hole asymmetry.

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Authors

  • Tim Wehling

    • University of Hamburg, Germany

  • Alexander Balatsky

    • Theoretical Division and Center for Integrated Nanotechnology, Los Alamos National Laboratory
    • Los Alamos National Laboratory
    • Theoretical Division and Center for Integrated Nanotechnology, Los Alamos National Laboratory, Los Alamos, NM 87545
    • T-Division, MS B 262, Los Alamos National Lab
    • Los Alamos National Lab

  • Misha Katsnelson

    • Institute for Molecules and Materials, Radboud University of Nijmegen
    • Radboud University Nijmegen, The Netherlands
    • Radboud University of Nijmegen, The Netherlands

  • Alexander Lichtenstein

    • Hamburg
    • University of Hamburg
    • University of Hamburg, Germany

  • Achim Rosch

    • University of Cologne, Germany