{
  "abstract": "Oxidizing Fe-doped BaTiO$_3$ is commonly expected to convert substitutional Fe$^{3+}$ acceptors into formal Fe$^{4+}$ centers. Yet, the experimentally accessible picture based on electron-paramagnetic resonance (EPR) is dominated by Fe$^{3+}$-related signatures, while Fe$^{4+}$ is not a straightforward observable. Here we show that this apparent discrepancy reflects the preferred location of the oxidizing hole: not on Fe, but on oxygen. Using density-functional theory with with occupation-matrix control and a piecewise-linearity-based Hubbard correction (DFT+$U$) for O-2$p$ states, we find that an oxygen-centered hole polaron is forming a Fe$^{3+}$-O$^{-}$ complex that is lower in energy than the formal Fe$^{4+}$ configuration. Our results identify ligand-hole formation as a favorable charge-compensation mechanism in oxidized Fe-doped BaTiO$_3$ and provide an explanation for the predominance of Fe$^{3+}$-based centers in spectroscopy. More broadly, they show how oxygen polarons can limit Fermi-level shifts and control the electronic response of acceptor-doped ferroelectric perovskites.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2605.18258",
  "author_total": 6,
  "authors": [
    {
      "name": "Mohammad Amirabbasi"
    },
    {
      "name": "Emre Erdem"
    },
    {
      "name": "Denis Sudarikov"
    },
    {
      "name": "Jochen Rohrer"
    },
    {
      "name": "Andreas Klein"
    },
    {
      "name": "Karsten Albe"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/4yj4vrmpbr9tz.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2605.18258",
  "fulltext_url": null,
  "id": "4yj4vrmpbr9tz",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2605.18258",
  "language": null,
  "licence": "CC-BY-NC-SA-4.0",
  "licence_label": "CC BY-NC-SA 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by-nc-sa/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cond-mat.mtrl-sci"
    ],
    [
      "openalex",
      "2505|Ferroelectric and Piezoelectric Materials"
    ]
  ],
  "openalex": "W7161702685",
  "pdf_url": "https://arxiv.org/pdf/2605.18258",
  "pmcid": null,
  "pmid": null,
  "published": "2026-05-18",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/4yj4vrmpbr9tz.ris",
  "sources": [
    {
      "first_seen": "2026-11-03T12:20:58Z",
      "native_id": "2605.18258",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2605.18258"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mtrl-sci",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Why hole polaron formation on oxygen is limiting the Fermi level in Fe acceptor doped BaTiO$_{3}$ under oxidizing conditions",
  "title_text": "Why hole polaron formation on oxygen is limiting the Fermi level in Fe acceptor doped BaTiO_3 under oxidizing conditions",
  "type": "preprint",
  "updated_at": "2026-11-05T15:20:17Z",
  "url": "https://research.draconitic.com/paper/4yj4vrmpbr9tz",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1021/acs.jpclett.6c01737",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}