Theory of inter-edge superexchange in zigzag edge magnetism

ORAL

Abstract

A graphene nanoribbon with zigzag edges has a gapped magnetic ground state with an antiferromagnetic inter-edge superexchange interaction. We present a theory based on the asymptotic properties of the Dirac-model ribbon wavefunction which predicts $W^{-2}$ and $W^{-1}$ ribbon-width dependences for the superexchange interaction strength and the gap respectively. Unlike in conventional superexchange we find that both the kinetic and exchange energy contributions favor the antiferromagnetic inter-edge coupling with a dominant role of exchange several times larger in magnitude than the kinetic energy contribution.

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Authors

  • Jeil Jung

    Department of Physics, University of Texas at Austin, USA

  • Tami Pereg-Barnea

    California Institute of Technology, Physics Department, California Institute of Technology, USA

  • Allan MacDonald

    Department of Physics, University of Texas at Austin, Department of Physics, University of Texas at Austin, USA, The University of Texas at Austin, University of Texas at Austin