{
  "abstract": "When insulators are excited by photons with above-gap energies, photo-doped carriers are transiently generated. Typically, orbital excitations weaken and broaden due to increased screening by these transient carriers, followed by a few-ps recovery via phonon thermalization. Here we report the observation of anomalous dynamics of many-body molecular orbital excitations in the narrow-gap Kondo insulator FeSb$_2$. In the pumped X-ray absorption spectra following excitation with 1~$μ$m photons, we observe a transient transfer of absorption intensity from the delocalized states at the main absorption peak to the localized molecular orbital states at the pre-edge. At the resonance of the low-energy molecular orbital excitations, the pumped resonant inelastic X-ray spectra show an approximately 30\\% intensity increase at a pump fluence of 11 mJ/cm$^2$ concomitant with the emergence of an energy gain feature. While the energy gain feature disappears after about 1-2~ps, the increased molecular orbital excitation intensities partially persist for at least 50~ps with no discernible energy shift. These observations require the invocation of a many-body excitation picture beyond single particle population changes.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.27630",
  "author_total": 17,
  "authors": [
    {
      "name": "Ke-Jun Xu"
    },
    {
      "name": "Nathan Giles-Donovan"
    },
    {
      "name": "Paulina Majchrzak"
    },
    {
      "name": "Abhi Suthar"
    },
    {
      "name": "Matthias Hepting"
    },
    {
      "name": "Marco Trento"
    },
    {
      "name": "Giacomo Ghiringhelli"
    },
    {
      "name": "Elizabeth Skoropata"
    },
    {
      "name": "Hiroki Ueda"
    },
    {
      "name": "Eugenio Paris"
    },
    {
      "name": "Biaolong Liu"
    },
    {
      "name": "Elia Razzoli"
    },
    {
      "name": "Wei-Sheng Lee"
    },
    {
      "name": "Thomas P. Devereaux"
    },
    {
      "name": "Zhi-Xun Shen"
    },
    {
      "name": "Dung-Hai Lee"
    },
    {
      "name": "Robert J. Birgeneau"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/9s0n4p9vfmzqv.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.27630",
  "fulltext_url": null,
  "id": "9s0n4p9vfmzqv",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.27630",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cond-mat.mtrl-sci"
    ],
    [
      "arxiv",
      "cond-mat.str-el"
    ],
    [
      "openalex",
      "3108|X-ray Spectroscopy and Fluorescence Analysis"
    ]
  ],
  "openalex": "W7223130988",
  "pdf_url": "https://arxiv.org/pdf/2610.27630",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-20",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/9s0n4p9vfmzqv.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:04Z",
      "native_id": "2610.27630",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.27630"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mtrl-sci",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Persistent Photo-Enhancement of Molecular Orbital Excitations in the Kondo Insulator FeSb$_2$",
  "title_text": "Persistent Photo-Enhancement of Molecular Orbital Excitations in the Kondo Insulator FeSb_2",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:04Z",
  "url": "https://research.draconitic.com/paper/9s0n4p9vfmzqv",
  "venue": "arXiv",
  "versions": []
}