Theory of Magnetic Edge States in Chiral Graphene Nanoribbons

ORAL

Abstract

Using a model Hamiltonian approach including electron Coulomb interactions, we systematically investigate the electronic structure and magnetic properties of chiral graphene nanoribbons. We show that the presence of magnetic edge states is an intrinsic feature of any smooth graphene nanoribbons with chiral edges, and discover a number of structure-property relations. Specifically, we describe how the edge-state energy gap, zone-boundary edge-state energy splitting, and magnetic moment per edge length depend on the nanoribbon width and chiral angle. The role of environmental screening effects is also studied. Our results address a recent experimental observation of signatures of magnetic ordering at smooth edges of chiral graphene nanoribbons and provide an avenue towards tuning their properties via the structural and environmental degrees of freedom. This work was supported by National Science Foundation Grant No. DMR10-1006184, the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and the ONR MURI program. RBC acknowledges financial support from Brazilian agencies CNPq, FAPERJ and INCT-Nanomateriais de Carbono.

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Authors

  • Rodrigo Capaz

    Instituto de Fisica, Universidade Federal do Rio de Janeiro, Universidade Federal de Rio de Janeiro, Phys Dept. UC Berkeley

  • Oleg Yazyev

    Department of Physics, U. C. Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory

  • Steven G. Louie

    University of California, Berkeley and Lawrence Berkeley National Laboratory, Department of Physics, University of California at Berkeley, and Materials Sciences Division, Lawrence Berkeley National Lab, UC Berkeley, Department of Physics, U. C. Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory, University of California at Berkeley and Lawrence Berkeley National Laboratory, University of California-Berkeley and Lawrence Berkeley National Lab, Department of Physics, University of California at Berkeley, Phys Dept. UC Berkeley, Department of Physics, University of California, Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, University of California at Berkeley and Lawrence Berkeley National Lab