{
  "id": "2204.11498",
  "version": "v1",
  "published": "2022-04-25T08:27:26.000Z",
  "updated": "2022-04-25T08:27:26.000Z",
  "title": "Reduced effective magnetization and damping by slowly-relaxing impurities in strained $γ$-$\\mathrm{Fe_2O_3}$ thin films",
  "authors": [
    "Manuel Müller",
    "Monika Scheufele",
    "Janine Gückelhorn",
    "Luis Flacke",
    "Mathias Weiler",
    "Hans Huebl",
    "Stephan Geprägs",
    "Rudolf Gross",
    "Matthias Althammer"
  ],
  "comment": "10 pages, 8 figures",
  "categories": [
    "cond-mat.mes-hall"
  ],
  "abstract": "We study the static and dynamic magnetic properties of epitaxially strained $\\gamma$-$\\mathrm{Fe_2O_3}$ (maghemite) thin films grown via pulsed-laser deposition on MgO substrates by SQUID magnetometry and cryogenic broadband ferromagnetic resonance experiments. SQUID magnetometry measurements reveal hysteretic magnetization curves for magnetic fields applied both in- and out of the sample plane. From the magnetization dynamics of our thin films, we find a small negative effective magnetization in agreement with a strain induced perpendicular magnetic anisotropy. Moreover, we observe a non-linear evolution of the ferromagnetic resonance-linewidth as function of the microwave frequency and explain this finding with a model based on slowly relaxing impurities, the so-called slow relaxor model. By investigating the magnetization dynamics in our maghemite thin films as a function of frequency and temperature, we can isolate the temperature dependent contribution of the slowly relaxing impurities to the resonance linewidth and, in particular, observe a sign change in the effective magnetization. This finding provides evidence for a transition of the magnetic anisotropy from a perpendicular easy axis to an easy in-plane anisotropy for reduced temperatures.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2022-04-25T08:27:26.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "thin films",
      "reduced effective magnetization",
      "broadband ferromagnetic resonance experiments",
      "magnetometry measurements reveal hysteretic",
      "slowly-relaxing impurities"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 10,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}