{
  "id": "1306.0469",
  "version": "v1",
  "published": "2013-06-03T15:48:52.000Z",
  "updated": "2013-06-03T15:48:52.000Z",
  "title": "Dynamic nuclear polarization in InGaAs/GaAs and GaAs/AlGaAs quantum dots under non-resonant ultra-low power optical excitation",
  "authors": [
    "J. Puebla",
    "E. A. Chekhovich",
    "M. Hopkinson",
    "P. Senellart",
    "A. Lemaitre",
    "M. S. Skolnick",
    "A. I. Tartakovskii"
  ],
  "comment": "Submitted to Phys. Rev. B",
  "journal": "Phys. Rev. B 88, 045306 (2013)",
  "doi": "10.1103/PhysRevB.88.045306",
  "categories": [
    "cond-mat.mes-hall"
  ],
  "abstract": "We study experimentally the dependence of dynamic nuclear spin polarization on the power of non-resonant optical excitation in two types of individual neutral semiconductor quantum dots: InGaAs/GaAs and GaAs/AlGaAs. We show that the mechanism of nuclear spin pumping via second order recombination of optically forbidden (''dark'') exciton states recently reported in InP/GaInP quantum dots [Phys. Rev. B 83, 125318 (2011)] is relevant for material systems considered in this work. In the InGaAs/GaAs dots this nuclear spin polarization mechanism is particularly pronounced, resulting in Overhauser shifts up to ~80 micro-eV achieved at optical excitation power ~1000 times smaller than the power required to saturate ground state excitons. The Overhauser shifts observed at low-power optical pumping in the interface GaAs/AlGaAs dots are generally found to be smaller (up to ~40 micro-eV). Furthermore in GaAs/AlGaAs we observe dot-to-dot variation and even sign reversal of the Overhauser shift which is attributed to dark-bright exciton mixing originating from electron-hole exchange interaction in dots with reduced symmetry. Nuclear spin polarization degrees reported in this work under ultra-low power optical pumping are comparable to those achieved by techniques such as resonant optical pumping or above-gap pumping with high power circularly polarized light. Dynamic nuclear polarization via second-order recombination of ''dark'' excitons may become a useful tool in single quantum dot applications, where manipulation of the nuclear spin environment or electron spin is required.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2013-06-03T15:48:52.000Z"
    }
  ],
  "analyses": {
    "subjects": [
      "78.67.Hc",
      "76.70.Fz",
      "73.21.La"
    ],
    "keywords": [
      "non-resonant ultra-low power optical excitation",
      "dynamic nuclear polarization",
      "gaas/algaas quantum dots",
      "nuclear spin polarization"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "publisher": "APS",
      "journal": "Physical Review B",
      "year": 2013,
      "month": "Jul",
      "volume": 88,
      "number": 4,
      "pages": "045306"
    },
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "adsabs": "2013PhRvB..88d5306P"
    }
  }
}