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