{
  "id": "1109.0174",
  "version": "v2",
  "published": "2011-09-01T12:32:52.000Z",
  "updated": "2011-10-14T15:38:41.000Z",
  "title": "Finite-size version of the excitonic instability in graphene quantum dots",
  "authors": [
    "Tomi Paananen",
    "Reinhold Egger"
  ],
  "comment": "9 pages, 10 figures, to appear in PRB",
  "journal": "Phys. Rev. B 84, 155456 (2011)",
  "doi": "10.1103/PhysRevB.84.155456",
  "categories": [
    "cond-mat.mes-hall",
    "cond-mat.str-el"
  ],
  "abstract": "By a combination of Hartree-Fock simulations, exact diagonalization, and perturbative calculations, we investigate the ground-state properties of disorder-free circular quantum dots formed in a graphene monolayer. Taking the reference chemical potential at the Dirac point, we study N \\leq 15 interacting particles, where the fine structure constant {\\alpha} parametrizes the Coulomb interaction. We explore three different theoretical concepts: (i) Sucher's positive projection (\"no-pair\") approach, (ii) a more general Hamiltonian conserving both N and the number of additional electron-hole pairs, and (iii) the full quantum electrodynamics (QED) problem, where only N is conserved. We find that electron-hole pair production is important for {\\alpha} 1. This corresponds to a reconstruction of the filled Dirac sea and is a finite-size version of the bulk excitonic instability. We also address the effects of an orbital magnetic field.",
  "revisions": [
    {
      "version": "v2",
      "updated": "2011-10-14T15:38:41.000Z"
    }
  ],
  "analyses": {
    "subjects": [
      "03.65.Pm",
      "73.22.Pr",
      "71.15.Rf",
      "73.21.La"
    ],
    "keywords": [
      "graphene quantum dots",
      "finite-size version",
      "bulk excitonic instability",
      "orbital magnetic field",
      "disorder-free circular quantum dots"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "publisher": "APS",
      "journal": "Physical Review B",
      "year": 2011,
      "month": "Oct",
      "volume": 84,
      "number": 15,
      "pages": 155456
    },
    "note": {
      "typesetting": "TeX",
      "pages": 9,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2011PhRvB..84o5456P"
    }
  }
}