{
  "id": "1506.07229",
  "version": "v1",
  "published": "2015-06-24T02:58:54.000Z",
  "updated": "2015-06-24T02:58:54.000Z",
  "title": "Negative static permittivity and violation of Kramers-Kronig relations in quasi-two-dimensional crystals",
  "authors": [
    "Vladimir U. Nazarov"
  ],
  "comment": "5 pages, 8 figures",
  "categories": [
    "cond-mat.mes-hall"
  ],
  "abstract": "We investigate the wave-vector and frequency-dependent screening of the electric field in atomically thin (quasi-two-dimensional) crystals of graphene and hexagonal boron nitride. We find that, above a critical wave-vector $q_c$, the static permittivity $\\varepsilon(q \\! > \\!q_c,\\omega \\! = \\!0)$ becomes negative and the Kramers-Kronig relations do not hold for $\\varepsilon(q \\! > \\! q_c,\\omega)$. Thus, in quasi-two-dimensional crystals, we reveal a robust physical confirmation of a proposition put forward decades ago (Kirzhnits, 1976), allowing for the breakdown of Kramers-Kronig relations and negative values of the static permittivity. In the vicinity of the critical wave-vector, we find a giant growth of the permittivity. We argue that these properties, being exceptional in the three-dimensional case, are common to quasi-two-dimensional crystals, while their discovery opens new pathways in the two-dimensional superconductivity.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-06-24T02:58:54.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "kramers-kronig relations",
      "quasi-two-dimensional crystals",
      "negative static permittivity",
      "critical wave-vector",
      "hexagonal boron nitride"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 5,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}