{
  "id": "1407.1528",
  "version": "v2",
  "published": "2014-07-06T18:48:10.000Z",
  "updated": "2015-03-17T20:26:13.000Z",
  "title": "Quantum Hall Bilayer as Pseudospin Magnet",
  "authors": [
    "O. Kyriienko",
    "K. Wierschem",
    "P. Sengupta",
    "I. A. Shelykh"
  ],
  "comment": "5 pages, 4 figures; corrected and close to printed version",
  "journal": "EPL 109, 57003 (2015)",
  "doi": "10.1209/0295-5075/109/57003",
  "categories": [
    "cond-mat.mes-hall"
  ],
  "abstract": "We revisit the physics of electron gas bilayers in the quantum Hall regime [Nature, 432 (2004) 691; Science, 305 (2004) 950], where transport and tunneling measurements provided evidence of a superfluid phase being present in the system. Previously, this behavior was explained by the possible formation of a BEC of excitons in the half-filled electron bilayers, where empty states play the role of holes. We discuss the fundamental difficulties with this scenario, and propose an alternative approach based on a treatment of the system as a pseudospin magnet. We show that the experimentally observed tunneling peak can be linked to the XY ferromagnet (FM) to Ising antiferromagnet (AFM) phase transition of the S=1/2 XXZ pseudospin model, driven by the change in total electron density. This transition is accompanied by a qualitative change in the nature of the low energy spin wave dispersion from a gapless linear mode in the XY-FM phase to a gapped, quadratic mode in the Ising-AFM phase.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2014-07-06T18:48:10.000Z",
      "title": "Quantum Hall Bilayers: Excitonic BEC or Pseudospin Antiferromagnet?",
      "abstract": "We revisit the physics of electron gas bilayers in the quantum Hall regime [Nature 432, 691 (2004); Science 305, 950 (2004)], where transport and tunneling measurements provided evidence of a superfluid phase being present in the system. Previously, this behavior was explained by the possible formation of a BEC of excitons in the half-filled electron bilayers, where empty states play the role of holes. We discuss the fundamental difficulties with this scenario, and propose an alternative approach based on a treatment of the system as a pseudospin antiferromagnet. We show that the experimentally observed tunneling peak can be linked to the XY-AFM to Ising-AFM phase transition of the S=1/2 XXZ pseudospin model, driven by the change in total electron density. This transition is accompanied by qualitative change in the nature of the low energy spin wave dispersion from gapless linear mode in the XY-AFM phase to gapped, quadratic mode in the Ising-AFM phase.",
      "comment": "5 pages, 4 figures",
      "journal": null,
      "doi": null
    },
    {
      "version": "v2",
      "updated": "2015-03-17T20:26:13.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "quantum hall bilayers",
      "pseudospin antiferromagnet",
      "excitonic bec",
      "low energy spin wave dispersion",
      "ising-afm phase"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "journal": "EPL (Europhysics Letters)",
      "year": 2015,
      "month": "Mar",
      "volume": 109,
      "number": 5,
      "pages": 57003
    },
    "note": {
      "typesetting": "TeX",
      "pages": 5,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2015EL....10957003K"
    }
  }
}