{
  "id": "0708.0029",
  "version": "v1",
  "published": "2007-07-31T21:17:37.000Z",
  "updated": "2007-07-31T21:17:37.000Z",
  "title": "Collective modes of CP(3) Skyrmion crystals in quantum Hall ferromagnets",
  "authors": [
    "R. Cote",
    "D. B. Boisvert",
    "J. Bourassa",
    "M. Boissonneault",
    "H. A. Fertig"
  ],
  "comment": "16 pages and 12 eps figures",
  "journal": "Phys. Rev. B 76, 125320 (2007)",
  "doi": "10.1103/PhysRevB.76.125320",
  "categories": [
    "cond-mat.mes-hall"
  ],
  "abstract": "The two-dimensional electron gas in a bilayer quantum Hall system can sustain an interlayer coherence at filling factor nu=1 even in the absence of tunneling between the layers. This system has low-energy charged excitations which may carry textures in real spin or pseudospin. Away from filling factor nu =1 a finite density of these is present in the ground state of the 2DEG and forms a crystal. Depending on the relative size of the various energy scales, such as tunneling (Delta_SAS), Zeeman coupling (Delta_Z) or electrical bias (Delta_b), these textured crystal states can involve spin, pseudospin, or both intertwined. In this article, we present a comprehensive numerical study of the collective excitations of these textured crystals using the GRPA. For the pure spin case, at finite Zeeman coupling the state is a Skyrmion crystal with a gapless phonon mode, and a separate Goldstone mode that arises from a broken U(1) symmetry. At zero Zeeman coupling, we demonstrate that the constituent Skyrmions break up, and the resulting state is a meron crystal with 4 gapless modes. In contrast, a pure pseudospin Skyrme crystal at finite tunneling has only the phonon mode. For Delta_SAS=0, the state evolves into a meron crystal and supports an extra gapless U(1) mode in addition to the phonon. For a CP(3) Skyrmion crystal, we find a U(1) gapless mode in the presence of the symmetry-breaking fields. In addition, a second mode with a very small gap is present in the spectrum.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2007-07-31T21:17:37.000Z"
    }
  ],
  "analyses": {
    "subjects": [
      "73.21.-b",
      "73.22.Lp",
      "73.20.Qt"
    ],
    "keywords": [
      "quantum hall ferromagnets",
      "skyrmion crystal",
      "collective modes",
      "bilayer quantum hall system",
      "meron crystal"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "publisher": "APS",
      "journal": "Physical Review B",
      "year": 2007,
      "month": "Sep",
      "volume": 76,
      "number": 12,
      "pages": 125320
    },
    "note": {
      "typesetting": "TeX",
      "pages": 16,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2007PhRvB..76l5320C"
    }
  }
}