{
  "id": "1610.04642",
  "version": "v1",
  "published": "2016-10-11T20:00:07.000Z",
  "updated": "2016-10-11T20:00:07.000Z",
  "title": "Impurities in a Chern insulator",
  "authors": [
    "Vibhuti Bhushan Jha",
    "Garima Rani",
    "R. Ganesh"
  ],
  "categories": [
    "cond-mat.mes-hall"
  ],
  "abstract": "Chern insulators arguably provide the simplest examples of topological phases. They are characterized by a topological invariant and can be identified by the presence of protected edge states. In this letter, we show that a local impurity in a Chern insulator induces a twofold response: bound states that carry a chiral current and a net current circulating around the impurity. This is a manifestation of broken time reversal symmetry and persists even for an infinitesimal impurity potential. To illustrate this, we consider a Coulomb impurity in the Haldane model. Working in the low-energy long-wavelength limit, we show that an infinitesimal impurity suffices to create bound states. We find analytic wavefunctions for the bound states and show that they carry a circulating current. In contrast, in the case of a trivial analogue -- graphene with a gap induced by a sublattice potential --bound states occur but carry no current. In the many body problem of the Haldane model at half-filling, we use a linear response approach to demonstrate a circulating current around the impurity. In all cases, our results compare well with numerical tight-binding results.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2016-10-11T20:00:07.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "broken time reversal symmetry",
      "haldane model",
      "low-energy long-wavelength limit",
      "linear response approach",
      "infinitesimal impurity potential"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}